Wow, that's a lot to ask for under $500! You might do best to save up in order to get what you really want. Since you're so specific, I would chat it up with some of the local music store owners. They get tons of stuff that comes through their stores, and they might be able to flag down some sweet deals if you're patient. You can certainly stand to relearn on that Ovation and that Fender that you have. Also, if you find a guitar without the pickups for which you're looking, you can always get the guitar and change the pickups later. Since you've got practice guitars right now, however, I'd simply keep saving and wait until the situation presents itself.
Myself, I'm an acoustic player, so I don't know much about electrics. I currently play a Taylor 214ce, a Mitchell Mandolin, and a Cordoba TM-CE Ukulele. I used to own an Ibanez Artcore semi-hollow, but I traded her in for a pretty decent Electric-Acoustic Epiphone 12-string. I used to fool around on my buddy's Strat, but I just could never get into it. I'm not much of a soloist; I've got a much more "singer-songwriter" feel. So take my advice for what it's worth -- not much.
I know that you didn't ask for a Telecaster, but this has always been the one electric that I would like to get. I think this is a reasonable price, even if it only has two humbuckers. There's actually a pretty large selection of well-priced teles on Amazon.
http://www.amazon.com/Fender-Telecaster-Electric-Sunfire-Fingerboard/dp/B009YZA1B0/ref=sr_1_19?s=musical-instruments&ie=UTF8&qid=1399772861&sr=1-19&keywords=fender+telecaster+72+deluxeIt's good to see that you are so concerned about tone color. I think it's very important to have good pickups whose sound resonates with you (pun intended). Again, I think the smartest thing that yo can do is look around in the local music stores where you live. There's always a deal to be had (especially with bargaining chips like that old Santa Rosa that you already have). If you could even get $100 for that guitar (and I have no idea what it might be worth), you could potentially buy up to one of those guitars that's just out of your budget.
Whenever I buy an instrument, I'm always sure to do my homework (which you've already done), but I'm also sure to look around in order to get the best possible deal.
Keep me posted with what you choose to do!
As to your other two goals:
1) Prepare well! The futures of young chemists hang in the balance.
2) I'm a marathoner -- if you're looking for fitness tips, PM me! I'm always happy to help.