JSM:
1) There are two issues here: "what's comfortable" and "what can deal with big recoil"? "Big recoil" generally means loads out past what you'd use for HUMAN personal defense. The Bisley grip frame is the acknowledged champ at handling "hand cannon class" recoil: 454Casull, 475/500 Linebaugh, the hottest 44Mag & 45LC+P on up. John Linebaugh won't build a handcannon with anything other than a Bisley grip frame. See also the video at:
http://customsixguns.com/
The other "big recoil grip frame" is the larger plowhandle used in SuperBlackHawks with barrels longer than 5.5". These big grip frames are usually seen with a "squareback" trigger guard but that was just a style thing...later variants did ship with round triggerguards ("Hunter" and Magnum Research BFR).
The smaller plowhandles and the Bird's Head are for smaller, handier guns used for less potent rounds...with some noted exceptions as they fit some hands better than the big grip frames. A few people report good recoil control with the Bird's Head, some of whom have smaller hands.
2) We've covered this...the grip frame itself was oversize for recoil control, the triggerguard itself was cosmetic (and now widely seen as a bad knucklewacker of an idea).
3) Hammer selection is all about setting the reach with your strong-side thumb on follow-up shots, versus how fast you can get the first shot off. It's a tradeoff.
Look at the "fast draw hammer" on this lady's gun:
http://bobmunden.com/gallery8.htm
All of Bob Munden's guns are set up with hammers like this. All follow-up shots have to be cocked with the off-hand - thumb reach is downright impossible. The first cock happens before the grip is fully acquired.
With the normal Blackhawk/Vaquero hammer and any of the grip frames smaller than the Bisley or SuperBlackHawk large, thumb reach to the hammer is very long but doable. Not real quick though. A lot of CAS/SASS shooters cock with the off-hand thumb for this reason. This technique means they're strictly limited to two-hand shooting in a real fight, which in my opinion is a good way to get dead. True, some people have big enough hands and long enough thumbs to allow solid strong-hand shooting. I'm not one of them despite my size (6'4") because I shoot "pinkie under" - pinkie slung under the grip frame, which stretches my thumb reach. That's why my gun wears a lower SBH hammer.
(I find that the SBH hammer still allows partial "fast draw" because it widens out at the pad and you can "catch" that width in the outermost thumb joint area.)
When you go to the bigger grip frames, thumb reach gets even crazier. Hence the SBH shipped with the lower-slung hammer that I adapted to my gun, while the Bisley drops the hammer reach even further.
If you're swapping parts around yourself, you want to drop the hammer reach enough for easy thumbing but not so far that it gets caught in your shooting hand's web. Hence you don't often see the low Bisley hammer teamed with the Bird's Head grip - and when you do, the shooter's hands are on the small side assuming they've set the gun up competently.
But there's no hard and fast rules - all of this varies by hand size, hand shape, shooting style, shooting type (target, combat, fastdraw) and recoil level desired.
, especially with harder recoiling guns like the 454 Casull, 475 and 500 Linebaugh....
