You can't go wrong with a Remington 870 Express.... so many modifications available...it's perfect.

For a reliable gun that's easy to break down and clean....Glock. Preferably a .40 or .45acp model. (no I don't care what you anti-Glock people think).

Rifle.... as far as .22LR goes... Ruger 10/22... tried, tested... tons of mods available to suit your needs...

High powered rifle.. tossup... go military, for the cheap and get a Mosin-Nagant 91/30... if you get the surplus ammo it's generally steel core (armor piercing) and cheap... either way it's a super hard hitting round..

More modern.. maybe a Remington 700 chambered in .300 Win Mag. Will drop about anything short of an elephant.