Alright, first I want to mention that I wanted to do such a project myself, and I had it all planned but I just got busy and then I forgot about it... Well, about the paying service I think it's best to use paypal because it is secure and cheap compared to other services. E-Gold is rubbish, I hate it. I recommend using CPanel or XPanel (I am not sure if they are different because I haven't worked with websites since a long time) and try to have Fantastico too because it is very efficient and easy to use by your customers (it will actually save you alot of time in technical support). Also I believe it's best to provide your customers with all scripting languages they need for the sites because some hosts do not provide particular languages and eventually people won't use their service. As a starter, I think you shouldn't use a huge server, you can start with a simple (but fast) server and then when your business starts running, you can expand your server.Concerning the security of your server, try using some good firewall and anti-virus, just in case some lamer tries to hack into the server.Well just want to wish you all the best luck