1. IBM Thinkpad A30
2. No, but I want to soon, IBM have one of the best compatibility records with Linux out of all laptops availible.
3. If you want value, Dell or Toshiba, if you want quality, IBM, also depends on what segment your looking into (Thin & light, Desktop Replacement, Office machine Workstation etc)
4. NFI
5. If the market can bear the price, then yes. A lot of the time, your paying marked up prices for luxury items (the very fastest CPU, a combo drive, Zip drives, Flash memory)
you can cut down a large chunk of this price without reducing functionality drastically.