Ecommerce beginner ! Auction site . Help appreciated !

I am planning to start an auction based site where members will create profiles and sell their own products. This idea should be so simple due to the numerous template themes available for auction sites on wordpress etc. However, my site will allow people to auction intangible products like mp3 files. The site would require a plug in allowing bidders to play a sample of the file (that has been uploaded by a user) and when the bidding price is met or the auction for that item has ended, they will be able to download that specific file.

I would say I'm pretty computer savvy but I do not write code and I have never created an ecommerce site, so a few tips to help me out would be much appreciated. Just to make you aware, I will be working on a shoestring budget.

• What platform would be best for starting this particular website? Wordpress, shopify etc?
• Would I be able to create a site like this by myself with plug ins or would I need a developer?
• I need a template that will allow me to earn commission off the auction.
• Like ebay, I will want to charge a small fee for each item uploaded by a user.
• Would I have to write my own terms and conditions or could I outsource this to a firm with the necessary details?
• At what stage would I have to register my business? after a certain amount of income ?

Thank you for your time!