The mini's gas system is "self-cleaning" meaning all you really need to do is wipe down the piston from time to time and clean the slide assembly as well. Rather low-maintenance guns, but of course a little upkeep is always good. Cleaning more often surely is NOT going to hurt, but its not super necessary. The blued guns I would clean much more often, but I own a stainless, I clean the internals most every time I shoot though, since I don't shoot a ton.
From what I have read, people like to use boxer primed ammo with the minis. Wolf black box is boxer primed, but their military classic is berdan. But I have read many people using brown bear, silver bear, barnaul (all the same really) ammo in their mini's without issue. Laquer coated ammo will require more chamber cleaning, however.
I would highly recommend reloading. My soon to be cost of reloading is about $4.20/box (20 rounds) as I figured it out. That is half what ammo on sale cost near me.
Check out this site for more mini-14 info, probably the best site around for the Mini family
http://perfectunion.com/vb/forumdisplay.php?f=86