That nick isn't that bad. You might hit it with a riffler file or some emory paper and smooth out any metal protruding out of it.
That retaining pin should come out and you should clean the FP channel. Many don't but the right way to do it is to pull it to be certain there isn't particulates in there that can bind things up and cause a slamfire down the road.
I would suggest you find yourself a 1/2" drive socket, set the socket down on a nice piece of concrete somewhere, put the bolt on it such that the head of the retaining pin will slip into the cavity inside the socket, and then try again. You want a nice flat bottomed punch for this operation, a nail set or center punch is just going to mushroom the tail of that pin and cause you more frustration in the long run. Those retaining pins weren't born there, I guarantee it'll come out!
If worst comes to worst and you need professional help, I'd contact Miurray (see Murray's gunsmithing link down at the bottom of the SKS-Files homepage) and ask what he'll charge you to get it out (and maybe you might have him just toss in a new FP into the bolt anyhow).
See this video for some pointers: