Yeah, I'm kinda skeptical to think that he's an energybender.
1) He doesn't come across as the spiritual type. I doubt the Lion Turtle (or any other spiritual user of Energybending) would teach him the secret of Energybending. It's just likely that, in his training as a chi blocker, he discovered the seat of bending powers, and knows how to exploit it to permanently negate bending powers.
2. Yes, if that happens, it will be awesome.
3. Branching out into other types of bending would also be awesome. Such as true Plantbending (being able to grow plants, change their species, make them grow/shoot thorns, etc, instead of Waterbending which can only move around plants that are already grown), Lightbending, Shadowbending, Soundbending, or something of that sort...even a return to, yes, Bloodbending, Sandbending, etc.
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)