RE: Pistol Killing Power
The 454 would probably give you more range, as far as killing faster it would depend on where you hit it and the design of the bullet. I have had deer die faster with my bow than with my slug gun shooting a 600 grn slug and delivering more than 2000 ft/lbs of energy.
And as it was eluded to above, it would depend on how well you shoot the gun. If it is too much gun for you and you don't shoot it well or are afraid of it then you may be better off using the 44 mag. I personally think the .357 is alright as long as you keep the range close. I think it makes a nice weapon if keep the deer within bow ranges. If I were to get a handgun to hunt with it it most likely be a nice .357, but I doubt I would try to use it beyond 35 or 40 yards.
You could also consider some of the pistols that shoot centerfire cartridges depending on where you live.
Paul