One guy can easily run all the admin-related stuff, manage tournaments and cash games, run bots, add bonuses and new games etc. etc.
You will however need a serious IT guy to run updates and add features.

We have no idea how long it will take you to break even. It could happen in one day or it could be never. We had days where 2 big players generated over 2 btc in rake, in a single day going at each other at a heads-up table. But then one of them left and we were stuck with people abusing bots and gtd tournaments.