What phones to use with Mobility lines?

Folks,

Please excuse my ignorance. I am just starting out on getting business phone service from Comcast.

I am getting two mobility lines. Comcast will provide me with the modem but not with the phone devices, correct? What phones should I get (or are recommended) to use these lines? I will have dedicated phone drops in addition to ethernet drops where the phones will be located. Should I get regular phones with RJ-11 jacks or IP phones so I can connect into my computer network? With the IP phone, I can still use the phone jack only if needed, right? 

I will start out with only 2 phone lines (1 phone + 1 fax) but depending on growth may get another phone line in the future. Also I would like to use the main phone line in two rooms (so 1 corded and 1 cordless handset?). I would like to keep my costs for the phones to a minimum as well. 

Thanks for any suggestions.