Concealment & Cover (pg 50) - This model never gains the DEF bonus from concealment or cover. It can get other effects (such as Prowl) though.
It's not explicitely said they can't get Stealth like Gargantuans, so they can.
Blast damage are half-strength or half pow attacks. A Direct Hit of any AOE weapon is "normal" damage, everything else in the AOE suffer blast damage.
Thus the target directly hit suffer an unboosted hit. That might seems counter-intuitive but it's basically (even unboosted) always strictly superior in term of damage, except for very very low damage attacks/...