Help needed regarding development of an e-commerce website

Hi,

I need some help regarding development of an e-commerce site in drupal.

Actually my site will have different types of users and each registered user will add his different products on the website like music files, videos etc. which will be available for sale on the front-end of the website. so, essentially there will be thousands of users selling their products, so, i am not sure about of:

1) What drupal version should i use?
2) Will marketplace feature of ubercart be useful to achieve this functionality?
3) How the payments to different account are going to be handled?

Please advise me!

Thanks,
Kul.