MarketPress with theme=SimpleMarket

I'm having several problems with MarketPress with the SimpleMarket theme:
1. upload of Kindle or ePub files won't work
2. adding a second product to shopping cart causes the first one to disappear
3. Shopping cart is subtracting 38 cents from the $8 price of a digital book
4. PDF version uploaded OK but purchasing it does not get you a "download"
Anybody have some experience with this combination? Anybody have a clue about what is going on?