Question 1: It's pretty much your call. A lot of forum members will say that megablox are so fragile that they should have a penality to their armor, but if you want to give them the bonus, no one can stop you.
Question 2: That's a tough call. I'd say 1 or 2 extra cp to the weapon's cost. Assuming the d6 can crit to increase the range, otherwise, it might not make enough of a difference.
Question 3: Ok, let's break it down...
- Start with the Medic stats (there's a few floating around in the forum, like this one
and this one
.) That will cover the healing.
- For the fireball, I'd buy it as a standard minifig ranged weapon. If you want something more complicated, dig around for some fire rule to add to it.
- The defense aura is pretty unique, so it needs some extra fudging. The simplest way I can think of would be this:
ARMOR SPELL (4 cp)
Gives +2 armor to this minifig and any minifig in the same squad.
If you think it's too good, you could require the minifig to use an action to keep it on. In that case, I'd cut the cost in half.
Hope this help!