Hello Ben, Welcome to the forum mate!
You can find the answer to anything you need to know about motorised bikes by reading through this forum and asking questions. There is a lot of brilliant information available here and many very experienced and helpful members.
I am new to this but in my opinion, the 2 stroke engines are cheap and alot of fun to learn on. They are also quite easy to install. The fuel is easy to work out, just remember, 2 stroke engines need 2 stroke oil
added to the fuel (gas) to lubricate them as they run and 4 stroke engines run on normal fuel (gas).