Yes to everything. Wario's Bite is far safer than Kirby's Inhale, so if you get a chance to get it, do it. It's a great move.
Shieldbreaker is fantastic, especially since Inhale is hard to use against the pointy sword characters Marth and Lucina. Again, if you see a chance to get it, do it. Shieldbreaker is better on Kirby than it is on them, because that means he gets a free fully charged Hammer Flip, which kills at 40% and below.
G&W's Chef ability is good. Again, he has pointy boxes of priority, so Inhaling him will be hard, and it's not like you can gimp him very easily with it. Also, he cannot bucket the food from Chef, which he could do in Brawl. He can still bucket Final Cutter though. Chef is generally just a good ability, I think most G&W mains underestimate how good it is, and thus underuse it.
And that's about it, I agree with your other thoughts, although I think Sonic's Homing ability is most likely a piece of crap, once people get the timing down they'll be able to dodge it almost always. I guess it's a potential kill move, so take it if you're desperate enough. And the only good part about Little Mac's ability is that I believe it has superarmor during the attack, but it is way too telegraphed to be worth it, and Inhale can help gimp him because offstage is his weakness, so overall it's not worth taking.