2018-01-19
A combined host/augment creature will get +2/+2 because it has augment.
2018-01-19
The +2/+2 is permanent. It doesn't wear off as the turn ends.
2018-01-19
You must be able to target a creature you control and a creature you don't control to cast Really Epic Punch. Note that you can target any creature you control, even if it isn't a host or doesn't have augment. It won't get +2/+2, but it will still fight.