How many months or weeks after hair transplant is it safe to perform 0.5 - 1 mm dermaroller microneedling on the recipient area?

Traction over the many years may cause permanent hair loss.  It may be in your interest to see a hair transplant doctor for your options.

It is best to contact your doctor about pre operative care and instructions since each doctor has a different regimen.  Some doctors advocate scalp exercises to loosen the scalp.

It is best to contact your doctor about post operative care and instructions since each doctor has a different regimen.  In general you can do anything at your stage. 

If you are considering a cosmetic surgery it would be in your interest to see a doctor for an examination to make sure you would be a candidate for surgery.

If the injury was severe enough to cause normal hair loss then it may affect your transplanted hairs.  Bleeding may be a sign that you dislodged a graft(s).

It is best to contact your doctor about post operative care and instructions since each doctor has a different regimen.  You should not be pulling out scabs.