Hello.

Suggestion: Buyer should be able to BUY more than one Item at once. May be adding an 'amount field' in the buying process? Right now it is only possible to buy one single item at once and than - in case buyer wants another item of the same product - he has to go back and buying this item a second time and so on....

It's already available the same as in Market. You just need to add an item multiple times.