As @voxel_pirate has said above, we know, judging by this picture, that there will be some sort of medic unit (Physician)
We also know that you will have the usual archetypes of combat unit - the tank, the healer, etc.
In response to your other questions, as @voxel_pirate has pointed out above, these are things we have very little knowledge about right now
Well, he will run through the idle animations I would presume, until there is a job for him to do! So, whether that be heal units, create healing supplies etc. we’ll just have to wait and see!
There has been discussions regarding revival of units, and this potentially could feed into the zombie apocalypse endgame, where your revival has failed and the unit has risen as a zombie, I’m sure you can guess the rest. Obviously this is all conjecture at the moment so we’ll have to wait and see!