-The skip button has been mentioned, and will be present in the final build. It's just a little thing I haven't gotten around to.
-The thing about adding hitstun is that if it were there, you would be utterly unstoppable, even if only some of the stronger attacks had it. Also, people would only use the attacks that have hitstun in them. I think that the issue right now is just that the first level has so many (too many) enemies in it right now, and is a little harder than intended. The idea was that the player has to make a tactical choice on which combo is going to work the best in a given instant, and getting better at the game involves knowing which combo to use for each situation. What I wanted to prevent was just button mashing. You can't just ZZZZZZZZ your way through the game. This sort of addresses the next point too, on the delay between combos. Again I believe this is due to the harder-than-intended first level, where those pauses that cannot be controlled unfairly punish the player with so many enemies. When the enemy volume has been corrected it will feel much better, I believe.
-A key press to advance the tutorial is a good idea, I can add that easily.
Thanks for the feedback!