Re: Pistols(whats a good one to buy ?)
A .357 would be ok for deer. I was just reading in Ken Waters "Pet Loads"(A set of books about favorite handloads, not pets) where he was working .357 loads. With heavy bullets, he felt it would be ok up to deer size animals. The .41 mag and up in calibre/size would be good choices. There are a number of newer large magnums available.
For a carry gun, on a tractor, that could hunt deer, you are looking primarily at two possibilities. A revolver, or single-shot. Why? Most magnums are not available in semi-auto's. Examples of a Revolver might be a S&W X29 or Ruger Redhawk. A single shot example is a TC Contender. There are others, within those manufacturers product lines and other manufacturers, but the ones I mention are time proven performers. Either revolver or single shot would be a nice entry in to the pistol field too(IMHO).
In the revolver series, you can fire a selection of magnum loads, in a soft or hollow point. In a single shot, you can shoot rounds that revolvers might fire, but can also get in to some rifle rounds and hybrids.
If I was in your position, I think a good pistol to buy would be a S&W 629 with 6" barrel, ported. Why? As a 44mag, it has reach and knockdown power. 44mag ammo is easily available. The ported barrel would help tame the recoil. You can also shoot 44-special, for plinking. Or, if the 44mag recoil is too much, a 44sp is still a good sized round for short range hunting.
I also like the classic one cartridge/two gun idea too; a 44 wheel gun matched with a .44 lever rifle would be a great combo. Pistol would make a nice 50 yard gun, the rifle a nice 100 yard gun.
Of note:
*Make sure the pistol fits you. I had a nice Ruger Blackhawk that had been tuned by a gunsmith. It shot really nice! But, it did not fit my hand, and I had problems shooting it offhand. On the bench, I could shoot well, but unsupported I could barely hit the target. It just did not fit me, even with different grips.
*Try it. As I mentioned earlier, see if you local ranges rent pistols, and give them a try. You want to be able to cary on the tractor, try the pistol in a holster(unloaded, of course) and sit in a chair. Move around like you would on the tractor. A good gunshop should be able to help you with that.
*If available, go to a pistol class. I have shot all my life. I had shot pistols on occasion, and did ok. I still found the introductery pistol class informative, and took some good points from it.
*Be aware of range. With a pistol you will probably want to limit your range to less than 50 yards. I read an article once that said not to exceed the range in which you can place all your shots on a paper plate. A paper plate is about the size of the primary vital zone on a deer or pig. I used to shoot(not competitively) silhouttes at 100 meters, about 112 yards. I could consistently hit pigs, off-hand/unsupported, with 8 of 8 rounds in my clip(previously owned ported Desert Eagle 44Mag semi-auto). However, my personally applied limit in the field was 50 yards. It is different shooting on the range than in the field(as I'm sure you are aware).
Now, above I mentioned magnums tend to not be available in semi-auto's. I will note here, that some are available, and that is what I used to carry in the field. My personal choice, after shooting many pistols, was a Magna-ported Desert Eagle in 44mag. It handled exceptionally well and was very accurate, although it is a somewhat heavy gun. To replace it(UPS stole it in shipping a couple years ago), I want to eventually get another Desert Eagle, and a revolver. My only issue with the Desert Eagle, was that it would only cycle the slide with full bore hot magnums. It did not like lead bullets(could clog gas port) or light loads(slide would not cycle). I have a friend who has a coupel 44 revolvers. By hand loading, he has 44sp loads that are on the money at 50 yards, and are great to plink with. He loaded 44mag loads that are right on at 100 yards. Both loads are right on at above mentioned ranges, without site adjustment...
I have shot .357mag, .44mag, 30-30, .30 Herret, 45-70, and .375JDJ from TC Contenders. The .375JDJ would hold a 2" group at 200yards(scoped, from a bench), and has harvested a number of Wyoming elk(it's a buddies). A 10" barreled Contender or similar handgun could certianly fit you bill. Some calibres, like the .45, can shoot snake shot very well, and one is available that can handle .45 or .410 shotshell.
The stuff I mentioned above runs about $600-1200.
All of the above, especially in this thread, is of course, IMHO, FWIW.