What happens if someone goes of their limit - for example say I have someone get up with 1gb transfer for their plan and they go over that - will their site just be blocked or will the company I am reselling for charge me for the extra badnwidth and then I will need to try to collect from those that I sold to?
Depends on the reseller package you go with. Most I have seen will mail you and let you know that X user has gone over his bandwidth by X mbs.
Who do you recommend? I want to sart small and grow. I'd like to find someone with a good start plan that I can easily expand over time.
How do you handle support questions? I know a decent amt about hosting but I am also no expert in php, cgi, etc. So if someone buys a plan from me and sends some question about getting a script to work & I don't have a clue how to help them, what should I do?
All you need to know about IS hosting. IF someone asks a question on php and you can help, then do so. But remember you are a host, your not expected to know everything about every scripting launguage. Politely reply saying "Sorry we do not support php questions, please see the php website www.php.net"