Please tell me what these are on my wall and how to fix them

Hi, Spotted a couple of dimples in my drywall ceiling, and trying to get an idea if this is something I should try to fix or if I need to call a drywall contractor. There is attic space over this ceiling -- no apparent signs of water damage that I can see. The drywall feels solid to the touch -- no crumbling or give to the drywall itself. Also, not seeing a super obvious sag, although depending on lighting and time of day, I can spot a few seams (house is 40+ years old). Tried putting a little pressure on the ceiling near the dimples I can see -- for most of them, no give or movement when I press, but for a couple, I can feel a small bit of movement, and looks like if I pushed hard enough, I could get the nail head to poke through. Looking for advice on best way to address where there is movement -- should I just add a couple of drywall screws to secure and patch things up, or am I better off calling a drywall contractor? Thanks for any help.

[left]We have a wall in one of our bedrooms that we want to take out but it is a load bearing wall. It was the front wall of a closet, which was about 12’ long by 4’ wide. The bedroom is upstairs so there is nothing above it, but there are ceiling joists that tie into the roof. I know it is load bearing because the joists in the attic that run perpendicular to the wall do not run the entire length of the room - one goes from the front of the room toward the back and ends right over this wall and the other joists are shorter and go from the back of the room to just over this wall (so those are only about 6’ in length. We want to remove the closet wall (we built a new closet space into the attic that is bigger) but I don’t know what size beam and studs I need to put in it’s place to carry the weight of that span. Any help would be appreciated.[/left]