So many questions...so little time...

I have five email accounts setup in Outlook 2010.... My boss has more than that... I don't think there is a limit.

Nothing will be faster than opening a mail directly on a web site like Gmail etc...

Nothing you do in Outlook will affect your phone's email account.

Going to Earthlinks web site to delete spam seems like an unnecessary step. Why not just do it once it reaches Outlook...and or using Outlooks mark as spam function might help in the future.