Engine stopped. Alternator? Blown cylinder? Bad transmission?

[BlazingSun]

Hey all. New to the site, specifically to ask this question. Admittedly, I do not know much about cars. A little info/back-story first:
I've got a 2000 Toyota Camry LE (over 225k miles) that's been leaking oil for a while now and, admittedly, I have run it whilest the oil is so low it doesn't register on the dipstick. Not smart, I know, but what can I say other than I hate being broke and handicapped (dependent on the car to get around)...In my defense, when I do add oil, it's usually only a quart or two low before it's registering at a good point on the dipstick. Battery is maybe 4 or 5 years old. Alternator never replaced (at least, since I've owned it, and I bought it @ 2004 with only 30k miles on it).

On Saturday, I was driving on the freeway when the RPMs jumped from @ 2000-2500rpm to over 5000rpm. Within about 15-20seconds, the engine completely cut out. Thankfully, was able to pull over in a safe spot and check the engine: Transmission-fluid was still full, Timing-belt still attached, hazard-flashers worked fine, didn't smell anything out of the ordinary, didn't see any smoke. Thought my car was just being...silly...so I added a quart of oil that I had just picked up, got back in the car, and started it back up. Transmission was lagging with switching to higher-gears. When I got off the freeway 3 miles down the road, it completely died on me again. When I tried restarting it, it was acting like the battery died. Yesterday, my neighbor gave me some more oil then helped me jumpstart the battery. While I let it sit there, the idle was rougher-than-normal for a minute or two, then go back to normal-idle. Waited about 20-30minutes, then turned it off, took a look under the engine, then started the car back up (started right up). Didn't smell anything. Saw a puff of smoke, but wasn't sure if that was from my engine or my neighbor smoking a cigarette about 30feet away (had the windows up, so didn't smell the smoke; just saw it blow by my passenger window...neighbor and I assumed it was either the cigarette or just the excess-oil that I accidently spilled pouring it into the engine). Wanted to drive it around...Bad decision! Transmission lagged when it came to switching to a higher-gear, engine definitely sounded off, then it died on me again when I stopped at a stop-sign. This time, while I was waiting the 30mins for the tow-truck, the hazard-flashers drained the battery to the point that it locked the doors and the key-fob-clicker wouldn't unlock (First time I've had to use the key to enter this car...at least, first time in a LONG time).
Hoping it's just the alternator/battery...but would that affect (effect?) the transmission? If the transmission or a cylinder blew, wouldn't I smell it (and how would it drain the battery?)? Did the engine just seize up from not having enough oil? (again, how would that affect the battery?)

So. Now I'm stuck. Any ideas?

[maxwedge]

You need a thorough electrical system analysis to start off with. Not really possible to diagnose this remotely.