For your purposes, I agree with others on the twelve gauge shotgun. Excellent destructive power at close and far ranges and relative ease of use. Buck shot for closer ranges and slugs for out to about 100yards.

For on your own property, a shotgun will probably fill all the roles you need. If you're set on getting a pistol as well, it depends on its primary purpose. For cheap practice and efficiency for killing animals, buy a .22 either revolver or automatic. If you plan on carrying around your property to defend against a human attacker, I would choose either the .38 special or the .380, depending on your preference for either a revolver or an automatic. Automatics in .380 tend to be straight blow back though, so they require a fair amount of strength to load.

For snakes a long handle shovel is usually sufficient (and probably safest). You can pick up and move non-venomous snakes and cut the heads off of venomous ones. Pin the snake behind the head with the blade and then just force it through like you're digging a hole. A sharp shovel will cut through just about anything. Plus the long handle gives you pretty good distance for safety.