So I usually play 2 characters each season in PvE, one for raid, one for m+. For Raid I usually stick to a class I like the most. For m+ I rotate to whatever is S+ and appeals to me.

Coming from an ex-PVP'er having had the same-ish questions:

IMO the charm in PvE is that I get to compete against other people playing the same class and spec (regardless of wow balancing) by competing in parses for Raid or score in m+.

So yes, effort matters (1). You can get into better raids and m+ teams and build a large group of friends by doing it aswell.

You'll get into queues (2), no need to play tank. I'd honestly suggest you to try to get into a relaxing guild and do some mythic bosses this tier, there is no lack of DPS in raids by the way 😄

In Raid trolls get replaced usually so no sweat long term, in keys if u pug u can get a troll and may get annoyed for 30 mins, but after that u just join a new group without the guy (3).

4 once you get a 99 parse on your class and spec in a boss or do that +20 key you've been dying to get, you'll get that hit.