Uses up a valuable coverage moveslot
I guess it is innovative, but it doesn't really sound good.
Expert Belt only boosts when it is super effective. Sharp Beak boosts Brave Bird no matter if the opponent is hit super effective, neutral, or resisted.
Items like Sharp Beak or Spooky plate let you deal better neutral damage and make it harder to switch into STAB moves in general. Expert Belt is usually only good if your moveset lets you hit a lot of things super effectively, and in that regard Talonflame and Aegislash actually don't hit a lot of things for SE damage, and anything they do hit for SE damage usually dies on the spot anyway.
Sharp Beak + Spooky Plate power up Brave Bird / Shadow Ball on all targets, not just super effective ones. Flying/Ghost are renowned for their neutral coverage, not so much their super effective coverage -- it's more important to have a consistently powerful STAB move for them than have powerful super effective moves sometimes and weaker neutral STAB moves at other times.
That's kind of a loaded question, and it depends on your team to see what fits best for it, but Mega Scizor, mega veanu, mega gyara, mega heracross, mega latias, mega latios, mega altilra, mega slowbro, megachomp, and mega abomasnow can some way or another fit that definition of bulky, but dishing out punishment
It's hard to answer that with just one mon, cuz it really depends on what kind of bulk you want.
Heatran, Landorus-T, Tyranitar, Keldeo, Kyurem-B, Jirachi, Hydreigon, and Magnezone all can be pretty solid scarfers.
Which of the ones you listed hits the hardest.
Heatran is more ranked for supportive capability, since it has utility moves like SR, Taunt, or Lava Plume to annoy things while walling. Heatran's not usually going to last the whole game, but the number of things its typing, bulk, and movepool allow it to support really help it fit into a lot of good OU cores.
