Section 1. As was posted here https://neocoregames.com/en/community/hub/buff-bug-with-channeledsalvo-skills there is an issue with "Concussive trauma" skill. Basically what is happening, it applies a buff after the ability goes on cooldown (in case of salvo\channeled and combo abilities after the player release the button), not after each bullet shot or melee attack. It is OK for single use abilities since they go on CD after every shot\hit, but not synergizes at all with channeled (salvo, combo) abilities. Also i haven't tested with abilities, which shot 3 bullets (i.e. burst shots) - probably the same issues is here too.

Section 2. "Battle dance" skill from "Close combat" tree doesn't work while characted has yellow\red suppression bar. Is it a bug or intended use of skill?

Section 3. "Overwhelm" skill from the same "Close combat" tree doesn't provide the buff for channeled abilities. Tested with Carthean Sword abilities:
1) first ability of sword (don't remember the name, the Combo one) - buff is applied after every hit;
2) Crimson path ability (second) - buff is applied after the player releases the button, NOT after every hit.