Tall fescue and KBG both make very nice lawns, but they are different species and each have their own pluses and minuses. Appearance wise KBG is usually the winner. It's spreading ability is a huge plus in my book. Scotts seed from the big box store is not something you should use, but grass1950 is right in that Scott's has developed and sells some great KBG seed. It all depends on what your landscape guy was planning on using. You can always supply the seeds you want him to put down. That way you know what you are getting. If you are planning on seeding this spring, then you will have issues with new grass dying off in the heat of summer unless you have your own personal superintendent monitoring it daily.

Assuming you stick to monthly watering between now and April, you have a shot at the lawn recovering without continued fungal issues. Winter's cooler temperatures work some magic in the soil. If you have sprayed fungus killers, I would suggest top dressing with 1/4 inch of compost (1/4 inch = 1 cubic yard per 1,000 cubic feet). You don't have to be too particular about applying it but you do need to be sure you sweep it all down into the surface of the grass. If you can look at it from the angle of the picture above and see any compost when you are done sweeping, then you are not done sweeping. I use a push broom to do that. You can use the back of a rake or anything that is not a stiff rake. Leaf rake is okay. The purpose of the compost is to replace and restore the population of microbes in your soil/sand. The fungicide did a number on your soil and will leave it unbalanced in a biological sense. In this state it is more susceptible to other diseases. Even a little bit of compost fixes that. And if you can find ordinary corn meal, you can apply that at 20 pounds per 1,000 square feet as often as you want to or can afford to. That helps to restore the population of organic disease fighting microbes.

Where are you in Texas? Are you willing to water deeply once per week in the summer, once per month in the winter, and once every 2 or 3 weeks in between? Lack of timely water is the biggest reason for failure of St Augustine. Probably fungal disease is the second biggest reason. How much shade do you get in the back? How old and/or playful are the dogs? Are they hole diggers? Will the dogs leave a soaker hose alone?

You are more in left field than you might think. Your neighbors are pushing you that direction. Unless you know of a specific drainage issue you're having, then don't bring in any more topsoil. Topsoil always changes your drainage. What you don't want to happen is to change it from good drainage to poor drainage. With a brand new home the builder likely left you with a perfectly profiled and draining landscape. That means the soil begins about 4 inches below the sill plate of the house and slopes away from the house for about 10 feet at least to a depth 6 inches further below the sill plate. It also means all the water drains toward the road or an official drain on your property. If you or your neighbors believe there might be a problem with the ability of the existing soil to maintain healthy planting, that can be fixed. Bringing in new topsoil means you have to test that soil instead of the old soil. It does not automatically fix anything. If you want a soil test, now would be a fine time. The soil test will fix the chemistry. Adding organic fertilizer will help fix the biology. Then growing grass and plants will further help the biology. After some months of growing stuff, your soil should be much improved over whatever it is now. Actually your weeds are secretly helping improve your soil's health. You have a lot of prep work in front of you before the grass gets delivered. You need it all done first. Don't let grass sit around on pallets or on the truck waiting for you to dig the sprinkler system. Start by NOT rototilling. Rototilling will not do whatever you think it will and it will ruin your existing soil structure. Your existing structure is still figuring itself out, so don't monkey with it. Sod will go down directly on the soil as is once the weeds are killed and raked away. Mow the weeds and kill them with Roundup spray once. Then start watering 2x per day to moisten the soil and try to grow new weed seeds. Water like that for a week. Then spray any new weeds that start to grow. Then you can do your plumbing. When you take soil out of the trenches, ALL THAT SOIL THAT CAME OUT GOES BACK INTO THE TRENCHES. Do not make the amateur mistake of leveling the tops of the trenches. There should be a mound on top of each one so that soil can settle back down to level with the rest of the soil. Otherwise in 2-3 years you'll see your trenches reappearing as the fluffy soil settles. Then you can put down your new sod. After the sod goes down it should be rolled with a water fillable roller to ensure the bottom of the new sod touches the top of the old soil. Roots will not grow down through the air to reach the soil below. You don't need to aerate. You are starting with newly profiled surface, so it should be relatively soft. Furthermore, aeration does not do what you think it does. At this point I'm not sure it does anything, so give us your reasons for wanting to aerate and we'll probably suggest something else. If any of this gets delayed, keep in mind that mowed weeds look like a lawn. Just keep them watered and mowed and you can push this project into fall if you want to. I just bought a house last summer. It's 90% weeds, so I can sympathize. Here is something I put together several years ago to help people like you. Basics of Lawn Care After reading numerous books and magazines on lawn care, caring for lawns at seven houses in my life, and reading numerous forums where real people write in to discuss their successes and failures, I have decided to side with the real people and dispense with the book and magazine authors. I don't know what star their planet rotates around but it's not mine. With that in mind, here is the collected wisdom of the Internet savvy homeowners and lawn care professionals summarized in a few words. If you follow the advice here you will have conquered at least 50% of all lawn problems. Once you have these three elements mastered, then you can worry about weeds (if you have any), dog spots, and striping your lawn. But if you are not doing these three things, they will be the first three things suggested for you to correct. 1. Watering Water deeply and infrequently. Deeply means at least an inch in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. Do not spread this out and water for 10 minutes every day. If your grass looks dry before the month/week is up, water longer next time. If that does not work, then you might have to water more than once per week during the summer's hottest period. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds. You will have to learn to judge when to water your own lawn. If you live in El Paso your watering will be different than if you live in Vermont. Adjust your watering to your type of grass, temperature, humidity, wind, and soil type. It is worth noting that this technique is used successfully by professionals in Phoenix, so...just sayin.' The other factors make a difference. If you normally water 1 inch per week and you get 1/2 inch of rain, then adjust and water only 1/2 inch that week. 2. Mowing Every week mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. However, bermuda, centipede, and bent grasses will become the most dense when they are mowed at the lowest setting on your mower. In fact there are special mowers that can mow these grasses down to 1/16 inch. Dense grass shades out weeds, keeps the soil cooler, and uses less water than thin grass. Tall grass can feed the deep roots you developed in #1 above. Tall grass does not grow faster than short grass nor does it look shaggy sooner. Once all your grass is at the same height, tall grass just looks plush. 3. Fertilizing Fertilize regularly. I fertilize 5 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above. Follow the directions on the bag and do not overdo it (unless you use organics in which case you may overdo it without fear of hurting anything). At this point you do not have to worry about weed and feed products - remember at this point you are just trying to grow grass, not perfect it. Besides once you are doing these three things correctly, your weed problems should go away without herbicide.