Downloadable sale, please help


I have a question to those who sell in their store items only for download (software, graphics, design etc). My shop was running but I decided to change everything and reorganize. I`m planning to sell design for download only instead of hardware. I have a few questions:

  1. How do I make this work?
  2. What do I have to change in my store? (setting)

    (it can be run at any time just I need to “throw away” hardware goods and put design and pictures)
  3. How do buyer receive link with download design automatically after payment?
  4. How to make link available only for 24h to download after purchase.
  5. Do I have to also set up thing with payment gate company?

    I will very appreciate your help. Thank You:p