It's called dehorning....
Most smiths charge $100-$150.
Basically you take the pistol apart, to the frame, like you should have done before dropping it into the ultra sonic cleaner....
Clean up all the little burrs etc on the internals with a jeweler a file set. Then polish the heck out of all the surfaces that move against each other.
Trigger jobs are fairly basic, but you need the proper tools an a jig.... It's really easy to f it up without a jig!
As far as the slide being hard to pull back. #### the hammer first, if it is easier then you need to radius the bottom of the slide where it contacts the hammer.
Feeding issues. First and foremost, throw away your mags. Go buy good ones! Then polish the feed ramp. Look at the barrel. Does it have a small ramp cut just on the bottom of the chamber or or from 3 o'clock to 9 o'clock? If its just on the bottom say from 5 to 7, then it won't feed anything but ball ammo very well.......
That's it in a nut shell. They write books about this so it's kinda hard to put in a forum post.....