They are for the most part interchangeable. If you were at a party, and they had a pile of sandwiches, you could say "I ate a whole sandwich",(just one) or, "I ate all the sandwiches". You could also say I ate the whole plate of sandwiches. usually "whole", is when you are talking about one thing, and "all" is about every piece.

よろしく

that's right.

フラー・ネイト

You're welcome :)

They are both understandable, it depends on the situation. If you are telling someone you take the bus to school, because it's cheap. you would probably say, taking the bus is cheap. But if someone asks you why you take the bus, you can say, the bus is cheap.