Adding Domains

I'm think its because I'm so used to being on a shared hosting plan and that's the only way I know. With my shared plan I have a main domain which I log in with and from there I can get to all my domains. Lets say I was to offer hosting for someone else then this would be a good setup for them.

I have another scenario where I would like to set up multiple staging servers with subversion enabled and have multiple designers/developers working on a different projects.

Both scenarios will obviously have different features enabled and restrictions imposed. I have had a look at the account plans that can be set up and a look at sub server settings which seem to applied to any given server. So I suppose my question is how would it be best to go about setting these two scenarios up? For the first scenario the account plan looks like the best option but I am basically looking to create a main domain login for all domains. For the second scenario of setting up multiple staging servers, I'm not so sure whether to go the account plan route or subserver route.

When I had a look at the sub-server setting there was much that I didn't know the meaning of. Although there are default options for everything I am hesitant to use these because I don't want to give too much access away. Additionally if I start changing everything from the default options I am worried that I'll get lost in a sea of nested options by nesting servers.

Thanks,

Darren