Gone through 250 rounds in my AR45 and have had one weak primer hit and 2 failures to feed that were magazine related (repeatable with those 2 mags not with others). And after every session the bolt rotates freely and the bolt carrier still moves very smoothly.
It looks like, as silly as it sounds, Automatic Transmission Fluid and high-temp bearing grease do work well enough. They last longer in the action without smoking unlike other lubricants.
Tried a flat trigger for my 1911 fullsize. Rather like it. Gives a better engagement and feels like a more even pull. If you have larger fingers you may want to try it.
A word of caution, since the trigger has less "meat" by being flat instead of concave you will want to check your holster to ensure that it covers the new trigger.
Also after a year I can say I really enjoy wood grips over rubber. To me, wood (or really any other stiff material) is nicer because it doesn't give, which means you don't need to use an overly strong grip to -well- grip.
As for checked grip versus smooth grips, I like smooth only if you have fore-grip checkering on the front of the frame. But that's a very personal thing. Just remember that the less checkering the more the weapon can slide.