Can someone help me gain an understanding about topics relating to PHP code optimization and traffic / amount of users, server specs or web hosting servers and the amount of users connected to a website at one time depending on specs, and how to look for a good web host for a website with users and a forum, etc. ?
I'm sorry this question is so unorganized, but do you get it? lol
Your question isn't clear, so let's try to steer it towards the information you're looking for.
1) Are you currently trying to decide on a hosting provider?
2) Are you working on a programming problem?
3) Are you trying to find information on why it's important to optimize code?