Don't have the BRB handy but I'm pretty sure it doesn't. You have to do three wounds which represent each crew member. The only time KB would have any effect is if there was some crazy a$$ warmachine with crew who had multiple wounds lol
Can't killing blow warmachine crew. They aren't on the list of things that killing blow works against. You can put a toad on it though, and 2 ripperdactyles will get ~10 S4 attacks that re-roll and 2 S4 attacks that don't, all at init 4. That will kill most warmachines (barring cauldron of blood which has enough attacks and initiative to be a threat to you; and anvil of doom, which has insane armor).
Killing blow still doesn't work against it, but the Chaos Dwarf Earchquake Mortar can have a Slave Ogre crewman which has 3 wounds. That's a rough machine to go up against. Expecially when the Chaos Dwarf player pretty much only rolls Hits on his scatter die...
I'm not so sure about Rippers for WM hunting. I'll try it but I'll also probably run some Chamelons as a backup. You can turn them to not face the opponent when necessary and there is always the possibility of the Generals Inspiring presence being in range for turn 1. Also, once the FAQ is out and the Chiefs can join the units as I hope is intended, Ld 6 will help out also. I'm geeked to get a chief with the Stegadon Helm in with some Rippers.
I do think the bolas are better on paper. I see ripperdactls as guided missiles - also good for supporting. Just be wary that you opponent will try to get their frogged unit out of their way. But 3 rippers in and of themselves won't mangle a big unit. They are for support. Terradons are for guerrilla war.
One thing I'd like to add to this discussion, both units are now Ld5. Since you will be operating outside of the general's bubble, this will come into play. For me, the Ripperdactyls are the more reliable choice. On turn 1, they just need to vanguard up enough to be still in range of the general, then use their 20 inch flying move to get somewhere they can charge a warmachine. You can do the same thing for terradons with one key difference... terradons can panic. A smart player will shoot up the terradons and kill one of them off, now you have a Ld5 panic test which you will often fail. Ripperdactyls don't really need to fear this problem, as they are frenzied and won't panic. I see a unit of 3 rippers making it into every army I build, because they're just so cool. They can muck around with warmachines in the backfield early game, all the while making the blot toad unit paranoid, and once the battle lines meet, they can charge back in and commit their noble sacrifice.
Played two games against Dwarves today. Played one unit of Rippers, one Terra, 2 Chamo. The Rippers and Chamos did much better than the Terradons. The Rippers got into the backfield and just crushed crossbows, and warmachines in 3 straight turns. I love Toad Rage!
Not sure tbh, if your opponent is shooting at a Terradon unit enough to panic them you've probably lost the unit already (same with rippers actually). I don't think Ld will be an issue for panic, I do think it will be an issue for trying to stop your ripperdactyls charging the closest thing they can see. If you get the first turn all well and good because their vanguard move prevents them from charging, but in the event of not winning the first turn I can see them being a struggle to use well. I think Rippers could work well with a mobile Oldblood general (either on carnosaur or cold one), but with a Slann bunkered in or behind your battle line, not so much.