When I bought my Camaro about a month ago there was an issue with the door closing, which I should have fixed before it got worse. The door would close, but would have to be shut so hard that it's caused another problem: the interior panel is starting to separate. I'm posting pics so it's easier to see. The part of the door that hits the striker (the part that the handle controls, I'm assuming that's called the latch) needs forceful prodding from a screwdriver while opening the handle in order for it to move. Closing the door was an adventure. My 2 questions are:

1. What part(s) do I need to fix this?
2. How can I fix the door panel?

I've searched other posts on this but none had the exact same problem but I did find a helpful illustrative guide by (obviously) shoebox on how to take the panel off.

Thanks.