Re: Hungry Ghost Realm
It is possible that he does. As well as what Last Leaf shinobi has already correctly said about Kisame and his sword, there were also Jiroubou and Yoroi (from Kabuto's team) who could absorb any chakra when in contact of the opponent.
I think absorbing some techniques though might not be so productive. Tsunade described Fuuton rasenshruiken as acting more like a poison due to the concentration of hits with each tiny blade of chakra - I can't see even Pain being able to absorb an attack so dangerous many times. He's lucky really that Naruto himself is limited to a low number of uses of the attack.
Like others have said though I think the Heaven Realm has a very large reserve already from Nagato however, so any boost would only be temporary and note a necessity for battle.