A couple of questions. It looks like I have to remove the receiver cover to remove the iron sights/mount one of the rails. Is this correct? Does a red dot or halo mount to one of the rails (one looks like a weaver? rail - don't know what to call the other one) included with the gun without any additional hardware? Do I need another base/rings, etc? I looked at the owners manual and while it mentions the two additional bases it doesn't provide much info beyond that. Thanks for the assistance in advance.