I'm really sorry about that. We're going to add an invincibility period after getting slammed into a wall if the wall is directly above you :( This is a known issue and we sort of just play around it since we know it exists, but we absolutely need to fix it since it's a heartbreaker.
For the boomerang -- the direction the boomerang fires is related to where you are relative to the plot when you plant it. It'll always shoot out in the direction that you're "pointing" (i.e. draw a line between the seed and the center of the plot when you roll over it, that is the direction it'll fire). Good to hear you're not enjoying it, though! Always interested to hear what people dislike.