I love my Betta, and tried reading enough about them to make sure he is happy. This is what I know at best: I would definately give a betta at least 1/2 a gallon up to 2 gallons. I've read that actually giving them too much room hurts their health in the long run, and they become prone to illness. Those mini tanks with the undergravel system (with the airstone and mini air pump) are nice and can be found at wal-mart or any other pet store. As long as the water level it high enough where the bubbles from the air stone do not interfere with ALL of the surface area of the tank's water. Bettas do breath from the top, so disurbing that surface area will kill them or suffocate them pretty badly. The reason I recommend these tanks is that on top of filtering your betta's water, it also keeps the water moving a tad, enough to stop from algae REALLY en joying your betta's space. I've tried bowls with still water, and the algae kept coming back for more with a vengeance.
Any water will do, these guys are tough guys, but if you want to make the oober happy, get those mini fizz tablets (I forgot what they are actually called in the store, but you can find them almost anywhere, like walmart).
Temperature is another matter, again these guys are tough, my betta has taken some cold nights (thanks to roomates tampering with the air conditioning) but he did well. Sudden changes in temp is bad for ANY fish, so avoid that if possible, but do not fret over 63 degree times, it happens, and your betta will forgive you.
When it comes to food, I would suggest Hikari for bettas. My betta is one PICKY punk. I tried A LOT of other foods before I found one he would stick with.
When it comes to water changes, luckily this is not a huge pain. First off, water changes for me is about once a month or two months. second of all, since the tank is small, it takes about two seconds to change the water, without a mess. When changing the water I would do this: take out the betta with some of the old water and put into a cup. After I clean the rest of the water out and rubbing the sides of the tank just to get goop off the walls, I would fill the tank with some cool water, as to avoid algae already being there growing. Don't fill the tank ALL the way, leave enough where the old water with the betta in it can go in as well. And presto thats it! Oh yeah remember to put in the fizz tablet I mentioned earlier.
Yikes I wrote a lot... boredom does do this