Most critical is to have an overall plan that you come up with the help of your surgeon. Future hair loss and availability of donor region critical components in determining graft requirements.
Based on the pictures you provided it does appear you have a good donor region which can provide you 6000-7000 grafts over its lifetime without it appearing over harvested.
Zone 1-2 (refer to the web link) based on the pictures you provide will require roughly 3200-3350 grafts, zone 3 will require 2000 for high density and 1500 for moderate density. Your crown has just begun to miniaturize and medication options are best. However, you can also restore the crown (zone 4) with a HT procedure as well.
Most critical is that prevention is worth its weight in gold and you must be judicious with the use of your grafts. Considerations of whether you want the permanent scar of FUSS versus FUE harvesting are considerations but most important component of the procedure itself is the artistic skill set of your surgeon.
Good luck and any questions let us know,
Hard to tell without an in-person exam, but i would say that 2000-2500 would be a good estimate.
A medical regimen with Romaine and/or Finasteride would also be a good possibility to prevent continued rapid hair loss.
Before answering this questions, I would like to speak with you over the phone. We are both in California although in different parts of the state. What you need to understand the the supply/demand formula for estimating grafts that you need for the short and long term. You will clearly need a Master Plan for your hair loss so that throughout the process you never look abnormal. I would discuss this with you over the phone at no charge.
Hair transplant surgery recommendation is based on an examination and a mutual understanding between a doctor and patient of what is achievable with surgery. Any doctor can say you may need 1000 or 3000 grafts but if you don't understand what you will look like after the surgery, the number quote you want would be useless.