As for the mag it's likely getting caught on the rear locking tab/lug. Just put some crayon around it and insert/remove it a few times to see where it's catching then file a little from that area of the mag.
As to the bolt carrier going all the way forward: If you pull hard on it to the rear and release it at the most rearward point will it go forward into battery?
If not, try putting some grease/CLP/oil on the hammer and the bottom of the bolt carrier. (shooting a few hundred rounds will likely polish this area up as well). If that doesn't work I have another idea but try that one first...