Characteristics and user status

Hi Experts ,

I have following requirements

1. I have created a characteristics ex- APPROVED_AMOUNT and assigned it to notification

I want only cetain authorised person i.e APPROVAL1 or APPROVAL2 should able to enter the values.

rest other user are not allowed.

2.It should check the entry in the charcateristics feild- APPROVED _AMOUNT and based on the value

either APPROVAL1 (For less than 100000) or APPROVAL2(More than 10000) should enter it.

3. I have created the user status APP(Approved ). If user select this user status then charcteristics-APPROVED_AMOUNT cannot remain blank. User has to main that feild. Can you suggest any user exist.

Regards

Anil Kumar