Well...the Mini 14 has been around since what, the late 1970s? It's still going strong. That should tell you something about its quality. I've shot them but never owned one so I'm not an expert. What I do know is they don't jam and don't break, but usually are less accurate than an AR15. As far as the mags go I think you can use any Mini 14 mag in any Mini 14, but I'll let one of the guys who owns one give you a "for sure" answer.
Thanks , i have a 10/22 , ar 556, several semi auto handguns , a Blackhawk 9mm/357 convertible an american 308 predator and an american 223 ranch. Love them all and to own a mini only makes sense for me for my collection.