Answer 1

Cool map, good spacing overall but it suffers from some awkward placement of slopes and spikes/dust. For example, there are several slopes that either send you into spikes, or have dust on the wall next to them so its impossible to get a boost and collect the dust. There is also a series of slopes that send you into a deathzone (camera would fix this). Also a lack of checkpoints makes dying near the end unnecessarily punishing

Pretty good for a first map though!

Answer 2

It's better to connect all enemies at the end to the red flag.
This way you prevent the player from finishing the level too early.
Just shift-click on all enemies in the final room.
I leave my replay as it is, so you can also see what I'm talking about.

By no means it's a bad first try :)