Given your stated situation, your plan to address the soil and over seed this fall is sensible at this time. You can also address the dead rocky areas (and any drainage issues) with additional soil and start reducing weeds with application of WBG as temperatures and weather conditions allow.

The first thing you should do is put down calcitic lime at the high bag rate. I prefer Cal Turf Pro, but regular calcitic lime is fine. Don't buy dolomitic lime. Ignore those lime amounts. You will need to apply calcitic lime every 90 days for a few years.

Tiemco - why calcitic lime? I was under the impression that since I was low-ish in Mg (according to the soil test recommendations) that dolomitic would be best.

Grass1950- Should I apply a pre-emergent in the fall and again in the spring or just spot treat weeds as they appear (a large percentage of the lawn is weeds since it hasn't been kept up for years).

Your magnesium levels are in the low-normal range, your calcium levels are in the deficient range. Calcitic lime is faster acting as well, so it will raise your pH faster, but it still takes time. You can raise your Mg levels with epsom salts, which very soluble, and go into the soil with ease. That soil test is OK, but it's missing a CEC/TEC.

The CEC was 5.3 meq/100g.

It is not recommended to use pre-emergents in the fall except for APOA problems. Plus, all but one pre-emergent (and it is very expensive) will retard germination of grass seed and should not be used prior to sowing grass (min. 6-8 weeks). If your weed problem is prolific, you can apply WBG Max by spraying (tank or hose end spryer) the whole lawn (you can apply it twice during a season without harming the existing turf grass- wait 2 wks between applications and follow directions for temp. and weather conditions). You will want to wait 3-4 weeks (see WBG directions) after the last application before you overseed this fall as WBG can also interfere with grass seed germination.

"The CEC was 5.3 meq/100g."

Wow, that's pretty sandy soil. Your pH will probably increase faster after liming than a higher CEC soil due to the decrease in cation bonding sites. You will probably have to adjust your watering and fertilizer applications to deal with your soil's lack of nutrient and water holding capabilities. I would split up fertilizer applications, so if you are going to fertilize in September, do a half app on the first, and the other half about 3 weeks later. Watering one inch of water once per week is probably not going to be ideal. Two or three waterings a week at .5 or .33 inches respectively will probably be more beneficially to your grass. Adding organic material will raise your CEC a bit and give more structure you your soil, but that takes time.

What would be a good, cheap organic material to add over time? I've read on here about alfalfa pellets but I don't know if that is what you are talking about.

Mulched grass clippings, mulched tree leaves and clean compost are are some of the least expensive sources.

Compost is actually the most expensive organic material and should be used in special circumstances. Unless you have an unlimited supply of free compost, then stick to mulch mowing, finely mulched tree leaves, and I really like alfalfa pellets. Where I live compost costs me $75 per cubic yard delivered. The app rate is 1 cubic yard per 1,000 square feet, so the cost is $75 per 1,000 square feet. Whereas alfalfa costs more like $6 per 1,000 square feet. And I maintain that alfalfa is 10x better for the soil that compost - assuming you do not have sterile soil.

When I bring in fill material, I always use straight sand with horse poo in it. Local materials supplier sells it cheap. As delivered it is too hot for direct application unless you are trying to kill the underlying grass. In the end it is plain white sand. But after a year it looks like black earth with all the organic matter in it. Drop some into water and all the white sand falls to the bottom and the black organic stuff floats on top, so it is still sand but the organic matter really makes the difference. Whether the sand will require more frequent watering depends on other factors as well. Shade, humidity, wind, direct sunlight, clouds, grass type, mowing height, and competition from other plants all are factors bearing on the watering equation. One hour per week all at once is a good starting point. If you get runoff in the middle of that, stop immediately and let the soil rest for 15 minutes. Then resume watering until you get the full amount.

Trust tiemco to read your soil test. It's not his first time.

dchall, you have a point if it is costing you $75/sq.yd. Here it is $25/sq.yd. If you can lay down 1/3 of an inch of alfalfa for $6 per 1k sq ft. by all means that is cheaper.

I looked at Tractor Supply and there are tons of alfalfa products - Hay Pellets, Cubes, Oat Hay Cubes, regular Pellets, etc. What should I be looking for in a product that is suitable for lawn use (seems like most of these products are meant for horse feed).

I can't advise you on what product to buy, but I don't think Tractor Supply is where you want to buy it. At $12 per 50 pound bag, if you put 50 pounds down per 1k sq ft. that is less than an ounce of organic matter per sq ft. At that rate it would cost you over $200 per 1k sq ft to put down as much organic matter as a sq yd of compost would give you. dchall should be able to direct you to a wholesaler of alfalfa pellets that is much less expensive than Tractor Supply.

dchall has a lot of good advice, but in this case he is in error. It's been a week and he has not disputed my proposition (it just isn't possible). If an issue is open to debate, I try to refrain from contentious debate, but when advice is blatantly wrong, I just can't hold my tongue. Alfalfa pellets have their place as an organic fertilizer and minimal OM supplement, but it is not a cost effective source of OM when compared to good compost. The advantages of good compost, as it is also one of the best sources of humates and micro organisms, far outweigh the use of alfalfa or cotton seed or CGM as an OM source. Hands down, there just is not a more cost effective source of OM (forget the humates and microorgs) than compost. Do your own cost comparisons by weight or volumn and give alfalfa a 10:1 advantage if you like.