Yes, recharging in Level 1 could be done only every third wave or so, that might make it a bit more interesting while still letting the player "learn" the different waves for when it gets serious in Level 2.
No way to spend space bucks yet. I thought that using the small-range "blast" (activated using Spacebar on the keyboard) could use up a space coin (and no coins means that this can't be used), but alas this was rushed and now you get coins and it shows up as the "last kill count" in the main screen.