New User/License/routing

[alexbacon]

I hope I can explain this properly.  I would like to give one of my employees access to be able to make calls and receive calls via my business phone line.  I'm sure I need to purchase another license, which makes sense but I'm trying to figure out the best way to it and to get them set up. 

1. I would like them to have their own login to the business line, which I'm guessing the license assigned to them will do.  Am I correct in this assumption?  and do I need to do anything other than assign them a license and login information?
2. I'm not trying to give them their own phone number, I would like to just have them be an extension of the current business number so when they call out it shows as our business line and when they call in they will just enter their extension or wait and hear the option for their extension.  Is this correct in my thinking or is this not even a possibility?