I've owned a few through the years. While few of the Mini 14s can truly be called "accurate, each and everyone I have ever owned, shot, or been around went "bang" every time the trigger was pulled, and I never saw one jam (not saying they don't, just never seen one be a major problem). Have heard the Mini 30s are much more accurate than the semi auto AK knockoffs though.
Not sure whether new ones take the hi-caps, but can't imagine they don't.
As for home defense, .223 and lighter bullets that won't overpenetrate would be the way to go. The drawbacks (or perceived drawbacks) to the Mini are that they don't have accessory rails for flashlights, etc., and don't have pistol grips.
I have a Mini 14 Ranch, and will keep it for the same reasons you are looking at getting one. Do it and have fun.
RR