Hi Jaydeep,
Go to Personalize settings in the fixed assets workcenter and you can tick the checkbox for individual material to show the list
For the list of users who have the access to post the purchase order (non-stock) then you may try to create a approval process for them so that you can restrict future purchase orders to have a control, who are allowed to use IMAT in purchase order and who should not.
Thanks
Lokesh Sharma