If this is all new to you, I suggest buying a good training book like Daniels Running Formula (not perfect, but a good place to start learning about training).
For a new runner (or any runner for that matter), mile repeats at 5k pace is very demanding. If you're just trying to build endurance, I'd suggest somewhere in the range of your estimated (or actual) 10k to half-marathon pace. If you're trying to to do some race-pace work at 5k (i.e., you're training for that event), then 800s at 5k pace is a good starting point.
Tempo can be all kinds of paces: classic is also roughly half marathon pace. Tempo at 5k pace isn't really "tempo" the way most people think of it.
Good luck