Sure you can Brandon. Al you have to do is locate and buy the after market parts/accessories you want to install. I will say, it is much easier to 'customize' a pump gun, though, as there are more after market choices available as far as parts and accessories.

yes they can be changed you may be able to drill the forearm and mount the rails on the bottom fairly easily if you cant find a forearm with rails

Brandon, yes you can. Mossberg makes an SPX-Treme which you could probable find the stock kit or the pre-tactical configured shotgun : https://blog.nationalguntrader.com/2019/01/01/mossberg-930-spx-treme/