Generally, polishing a feed ramp isn't something that I would "talk someone through" but it's possible you could do it yourself. It's also possible you could over do it yourself and make it worse.
This is one of those times that I am going to recommend a trained gunsmith for you, it's something that is kind of important it's done right. It's not hard, or even technical, but we are talking about reliable performance here that needs to be 100% correct for real world use.
As for the trigger, generally speaking a factory trigger can be tuned and work just fine. If you can not achieve the type of pull, break and reset that you are looking for in a carry gun, then changing out the parts might be needed.
If you aren't familiar with tuning a trigger, there are plenty of on line sources, but again, I am going to shy away from talking you through it over the internet just because this is for a carry gun and NEEDS to be reliable 100% of the time. Again, it's not hard, it's just important to get it right.
As for the shooting, there are a couple of threads around with a standard target that is broken down into sections, and where you are hitting, shows exactly what you are doing "wrong".
Search through posts by Robocop10mm, Mark F and possibly Bob Wright. I can remember who posted it, but it's been posted in a couple of threads and it works perfectly.