Second question first, yes, TMCC boards are available for purchase. The conversion process to run the motor(s) is fairly straight forward. Get them from Electric Railroad Company, forum sponsor in the ads at the top of the page. When shopping, make sure you get the right style for the motors in your engine. The only thing that can get a little tricky is the physical mounting of the board, and if you want to add electro couplers.
When a TMCC engines hit an unpowered section of track, they will of course stop. The difference is when the power comes back on, they will just sit there waiting for a command from you. A conventional engine will take off at the set voltage when power is reapplied.