As for the rear sight, there's a set screw that can be tightened. If it still slips, try some blue loctite.
Polishing the striker helps some with the smoothness. I'm not for cutting springs, but if you cannot find a replacement, lighter spring, and still want a lighter pull, it's your gun. Just have a spare factory spring handy. On polishing, mainly the contact/wear points. Don't change any geometry. In my other stickied thread, the 2nd post details the points I first polished. Those are the main ones. The striker blocker is one to pay attention to. Also, break down your entire slide and clean it out. Gunk gets into the striker blocker spring sometimes and can end up in the striker channel (by poor design of the extractor). Keep that clean and it stays as smooth as can be.
The roll pin in the striker isn't hard to remove even if you don't have a good workbench. I do recommend some sort of soft jawed vise. Just be aware that the striker's plastic bits can come flying out once the pin is cleared. Replacing the indicator is easy if you have the proper pin punch.
Josh