1) There are a ton of threads on this topic. Might get some good info if you look around a bit.
2) Working out is all trial and error. There isn't one specific way to gain muscle and your training methods can depend on a lot of different things. But to answer your question, no, if you train biceps one day, you don't have to train triceps that same day. It's all preference. Just make sure you train all bodyparts equally. IE. Don't train biceps 5days a week and triceps once...ect.
And 48hours is usually a good amount of time between working out the same muscle group. But some people recover faster, some recover slower. And it depends on how well you help feed your body the necessary nutrients to repair your muscles the fastest.
3) Eat lots and make sure you are getting enough protein and nutrients each day. Again, you can use google or find threads on here to find examples of what to eat and when.