Get your bedlinen if you like but there's plenty here, all kinds and all price ranges.

Doha is is a terrible place to find books, DVDs, music and computer equipment.

If you like corn nuts and beef jerky bring a supply. I order them through Amazon.

Once you're here you can open a Shop&Ship with Aramex courier service and they'll provide you with a US mailbox and get your stuff shipped here twice a week.
Aramex

You'll open a bank account here and get local credit cards. That's really the best option although you could use your Visa/Mastercard if youy like but I don't see why.