Bubba: To buy weapons, click "Inventory" while you're on the level select screen.
DudeeduD: To return damage, use the Thorn Skin perk and the Mutant armor pieces.
Flying enemies are a poorly developed aspect to the series, in my opinion. You don't ever need melee units, and them being useless part of the time just makes it worse.
Ugh. Awful physics.
And yes, the cart should be fixed to the track. This is more of a car game than a roller coaster builder. It still wouldn't be enjoyable, though.
1/5.
There's no particularly fast way to get pixels. Just idle in the arena with auto-fight and auto-potion on (make sure you have enough defense that you'll actually earn money instead of burning it all on potions. How much you need depends on the area).
So, let me get this straight... I could pay $15 for this, or I could get, say, The Orange Box or the Baldur's Gate collection for about the same amount. It's not a bad game, it's just that the price point is insane.