you have unclear questions. However find below as answers.
1. You can have Hardware Service or Renting agreement with sister concern without a problem. If you want to purchase then you can purchase it from sister concern but it will attract Transfer Pricing Rules.
If you procure hardware as second hand goods from any body you will loose Income Tax Benefit.
2. You can allot fresh appointment letters to your current employee on Name of SEZ unit. It will treat as fresh employment.
If you just shift employee from DTA office to SEZ unit it will treat as reconstruction of business hence there is chance of loosing Income Tax Benefit.
3. For List of Benefits to SEZ unit visit www.sez-india.net