They aren't picky about their temperature, as long as it's not ridiculously high or low. They also aren't too picky with pH, but harder, alkaline water seems to be best for them.
A 2 foot tank may be okay. What is the gallonage on it?
As for numbers, you need 2-3 females per male. This is because the males are mating machines, and will continuely try to mate with the females. With just one female, all of the male's attention is on her, and she will become stressed out. With more females, his attention is spread out and each one gets some rest time. If you want 10, you'd have to have 7 females and 3 males, or POSSIBLY 6 females and 4 males. I would recommend the first though.
Yes, they eat their young. If you add in some hiding plants and plants (especially floating) then you should get some fry that survive. Or you could raise the fry seperate from the parents in a breeder net or fry tank.
They'll eat pretty much anything. Flakes are a good staple, and you can alternate in some high protein foods (frozen, live, freeze-dried) and some veggies too.
Platies can be sexed by the anal fin, which is the fin near where the tail and body connect. A female will have a fan-shaped anal fin, and a male will have a pointy one.
Also, before you breed, plan for fry. With the number of fish you want, you'll have a ton of fry, and you can quickly become overrun. Find somewhere to give/sell them too, should you have too many.
Also, take a look through the FAQs and Pinned Articles. All your questions were answered in there.

Also, you can search for topics on the same thing too. I know there's been lots, so you should be able to find some good advice in those. Good luck!