Marketpress on Multi user site

I want http://www.vrijeverkoop.nl to be a webshop that can be used by several users. I installed MarketPress, Multi-user etc.

Each user should be able to add products and should only be able to edit or delete his own products. Visitors can E-mail the shopowner!?

I have tried all possibilities from author to... etc

I also have 'problems' with the permalinks and I do not have a nice productpage etc. After saving Store Settings\Presentation no productpage was created?? etc etc

To be short: it is still a mess.

BTW: Something like Etsy would be nice.

Can you help? I could mail you the login?!

Kind regards,

Ruud Wiering