thank you for playing! i'm happy to report that most bugs you mentioned are known and have-been/will-be fixed for the next dd. at the time i hadn't figured out how to make the blue-guy swim down on mouse and keyboard. sorry for that. as for the game-design feedback.
from what i've seen and experienced the game really does play like ass on mouse and keyboard and i don't really know what i'm going to do about that. some people have recorded their gameplay and a lot of things you're describing also show up in their video's, but it's nice seeing it reiterated here from someone else. i will probably remove the big tree from the yellow-guy level and replace it with something else and add a (hopefully) easy grapple-zone for players to get accustomed to grappling.