Marushin m16a1 parts compatability

I just had a few questions about the Marushin m16a1, firstly, how do I remove remove the hand guard ring in the front and the front sight post? Secondly I had the bolt catch break on my the paddle part, could I install a real one in and then have the ability to use real mags without modifying the msg catch slot and just having to modify the mag lips and spring? Thanks!