I also have S.A. and live in the St.Pete area so I can relate. I completely agree with giventake about the watering. My front yard has 4 rotor heads and it takes 80mins to apply 3/4in of water. Here are a Few thing that work for me. 1. Mow High (3-4+in) and Frequently with a Sharp Blade 2. Postpone Fertilize and Herbicide Applications 3. Irrigate Uniformly 4. Irrigate Early (between 4-9am) 5. Let Your Lawn Tell You When It Needs Water You'll see spots in the lawn that turn bluish-gray, footprints that remain in the grass long after being made, and many leaf blades folded in half lengthwise. For Florida's sandy soils, 3/4 to 1 inch of water is generally sufficient. Do not water the lawn again until 30 to 50 percent of the lawn shows signs of wilt. There is a simple test you can do to determine how much time it takes to apply 3/4 to 1" of water. (see link below) I put my cans out the night before the sprinklers are set to run then measure in the morning. Here is a link that might be useful: How to Calibrate Your Sprinkler System

Basically, when St.Augustine turns brown and dry, it is dead. It will not come back unlike bermuda. since the grass is dead, all of the weeds you mebntion simply are opportunistic. Don't know what type of grass 'dad' has but SA is never scalped. Perhaps the owner resodded the lawn but didn't follow through with proper watering. Now, second concern, what is the tree/shade situation? SA tolerates some shade but it needs 4-5 hours daily of direct sun. Also, if you have sandy soil it may have been a problem to get enough water on the lawn. Pick the neighbor's brain if his lawn looks good.

If you can find a pronged rake or hoe. I use an old 5 tined hand held tool that came with the house and a curved pitchfork like long handled tool called a potato fork/rake. The tines of the potato gaget curve down from the long handle. Both tools I run under the surface and lift. This will help with plants that have runners or fiberous roots. Another good tool is to go to a second hand store and get a used carving knife. Use it to stick in the ground and move around plants with tap roots. You can cut the tap root on many far enough below the surface that many will not return.

I was sort of hoping you'd be living in Blythe or somewhere where you needed extra water, but no. You will almost never need to water more than once every 2 weeks. On the days when the Santa Ana winds blow, if that lasts longer than 2 days, you might want to water once before your 2 weeks are up. But you do need to water a full inch when you water. If runoff is an issue for you, we have a cure for that, but I'll wait for you to ask. Or if your soil is unduly hard - same solution. Ask your lawn mower guy to raise the deck all the way to the top for you. Still mow every other week. If he refuses, remind him there are other lawn care professionals who will do it. St Augustine really performs a lot (LOT) better when mowed high. It does not grow any faster when mowed high. In fact there are no minuses to mowing taller. You don't have to go to my mowing extreme, but here's a picture of my chow chow walking through the tall St Augustine at my old house...All you can see is the top of her tail and ears, thus demonstrating that St Augustine does just fine all the way up to 32 inches high. That grass had no fertilizer in years. One part in the shade (but still with droughts and 100+ summer temps) needed no irrigation at all for 36 months. If you mow your grass at 3.5 to 4 inches you'll get much better rooting and the ability to withstand prolonged dry spells. That does look like the same fungal disease I get. I get it because sometimes I don't get the tree leaves off the grass before the dew hits it. In your area you have dew 365 days a year, so you absolutely cannot leave anything on the grass. My wife used to leave garden trash on the grass until I 'splained it to her that just leaving it there overnight started the disease process. I'm not sure which disease it is but for me (being organic) the solution is always the same product - corn meal. Corn meal starts a biological chain reaction that eventually (a week or two) kills the disease. Then in 3 weeks you should see the grass returning, by stolons, back to the bare spot. You can try using a chemical fungicide if you prefer. I can't recommend one, because I never use them. The corn meal rate is 20 pounds per 1,000 square feet. Do the entire lawn because you don't know where it starts or stops. And if you only do the bad spots, you'll have deep green grass in those spots because corn meal is an organic fertilizer. Pick one or the other to try. If you try the chemical and you're not happy with it, you can't use corn meal later, because that biological chain reaction requires healthy soil microbes and the fungicide kills the required beneficial fungi.