Howdy neighbor!
Sort of, DFW area here also!
Good call on cleaning it out. I inherited a similar mess when I bought my house some 20+ years ago, although not to the extent you are dealing with. I did not have to do a drain but have since had a full drain done when I finally had the pool refinished 16 years ago and then a partial drain several years ago and I too worried about draining the pool and floating it. It is always a risk, of course on the full drain, the company doing the remodel did it and pulled the plug at the bottom of the drain to discharge any water under the pool.
My two cents on it, for what it is worth and some may disagree:
--yes, get that $65 a day sump pump from HDepot and start in the shallow end (or a step to get started) to avoid sucking in debris...those things work pretty fast although my pool is not as big as yours...and then just keep moving it lower and lower as more water is drained
--you should have a sewer main/clean-out out front somewhere...usually will be near front outside faucet/water shut-off box...maybe previous owner knows if it is not clearly identifiable (mine has rubber cap on it, 5 or 6" diameter PVC that leads directly to sewer)...this will keep you from flooding your yard, neighbors yard, and from staining the streets and sidewalks with that nasty water...if you do not have or cannot find the clean-out, ask HDepot for a couple extra of the hoses (they never charge me for extras and always ask how many I need--50 ft each I think) that attach to the pump so you can hopefully reach (or get close) to a curb/storm drain and push the water down there with minimal running through the yards and streets
--as you drain more of the water, it will expose and make it easier to clear the large debris from the lowest points in the pool, so kind of work in levels if you will to make the job less strenuous pulling the leaves, frogs, and whatever through less water depth
--I too fear the horror stories of the pool float and even though it has (and looks to be for a while) awfully dry around here weather-wise and since most of us do not have high water tables, you never know...maybe what you or someone earlier suggested is to take it to about a foot/foot and a half deep and then refill...that will allow you to easily get all the junk out, power wash the sides for the most part and then refill...replacing 4/5 or so of your water will be enough to take it from "creature of the black lagoon" to just "murky", which is very manageable with shock at that point
--you will want your pump and filter in good shape to facilitate things once you have refilled, so if you know either is truly bad (they look pretty old, my original pump was that one in the picture and my original filter was a sand version that looks like picture also), you will probably want to replace so you can get right to circulating the water once you drain and refill...this is one of the disagree points many may have, but if you replace the filter, my vote is sand...I know people with DE and cartridge and mine is by far less maintenance and it keeps my pool sparkly...but don't replace what doesn't need to be until you have to
--kudos on former spouse helping out, if we all only had as considerate one of those lol...if he is electrically handy, he can do the light and the pump (actually if he is reasonably handy, the filter too--PVC is just tinker toys for adults!!!)--when I had my pool remodeled, I completely rebuilt my entire pool pad...I am reasonably handy but no expert, so having free labor on that stuff is a big money saver
--in time you may want to replaster and retile, but I would see where you are after getting it cleaned up...sure it may not be perfect with odd paint in different areas but that was how my pool was until I could save up to have it redone correctly...believe me, the difference will be so night and day with it cleaned and chemically treated that it will take you a few summers before having it done right will seem like that big of a deal...plus, you might be surprised at how good it looks once you get it done, it may be good to go for much longer than you think...you were going to have to do this cleanup no matter (or pay someone to do it) before plaster and tile, so the only thing you are spending extra for is new water by not remodeling right now and that really isn't that much in the grand scheme--just look at a bill or online at your water provider and see what your per 1000 gallon cost is and that will give you a good idea of the refill cost
--I do agree with those that said replace the light with an LED model...less electricity and far longer bulb life makes it the best cost in the long run...I sprang for the color changing one and it was only $90 on sale more than the white and really cool to have many color options!!! plus old halogen lights, once you break the seal (even with new gasket which is must), sometimes they never get water tight again...but for initial cost savings, you do not have to replace light before you clean and refill pool--they are easily replaceable with pool full, they have long cord to bring them to the top
--finally and most important if you are doing this weekend, SUNBLOCK and HYDRATE!!! It is supposed to be 107 and 104 degrees saturday and sunday...geez, cannot believe it...we usually get to July before we get triple digits! This may be a loooooong hot summer...and one you will be glad to have working pool for!!!
I will keep an eye on this thread so keep us posted how it is going. Definitely shout with any questions...lots of good, knowledgeable folks around here who always glad to help (as you can already see). Of course, you know, when you get it all up and running and have that first pool party/BBQ, everyone that posted to your thread gets an automatic invite! HAHAHA! Good luck, it will be so worth it in the long run...and if we have a hot dry summer, the amount you will NOT spend on mosquito repellent will go a long way to paying for pool chemicals!