I have all three, but I don't POP my Cox account. Too much spam in it.
The answer to your question, though, about the "from" address is: you can set the "from" address to your cox account, so even if you reply from your BB, that's what they'll see.
Go here: https://webclient.blackberry.net/Web...ite=mycingular
Then click on "Profile", then "Sent From Address". You can change that to your Cox account, once you POP it to your BB.
When it comes to multiple "from" accounts, you can't do it without BIS 2.0, which Cingular hasn't upgraded to, yet. However, you don't seem to have to worry about that just yet, if at all.
Hope that helps.