What is my norwood grade? Is 3500- 4000 grafts FUE enough for me to get a full cover + high density? (Photos)

You are more than likely heading to be a Norwood seven. You need to speak to a highly experienced clinic that can handle your case which will not be just one single surgery. Yes you’re going to need PRP. You still need to consider finasteride. Most of the hype around finasteride is just that. Hype. It’s very rare to have sexual side effects. I hope you’ve consult with someone soon have a good day.

Hair transplant surgery is not about "how many grafts" you need, but about how a doctor can match your goals and expectations.

It appears that due to the hair loss already occurring at your young age, you are heading for a NW 6 or 7 level of baldness. Hair Transplant by FUE is a good option for you but keep in mind the best chance for success to expand your available donor area. This can be accomplished by an experienced doctor utilizing grafts from your beard and body.
We encourage you to further consult with a physician for any medical advice. I am always available for a free consultation as well.
For an example of a NW 7 patient regaining a full head hair watch the video or use the link below

Your pattern at the age of 24 is class 6.Due to your extensive pattern and young age I would not recommend hair transplantation at this time.All efforts should be directed at maintaining the existing hair and preventing further loss.If you are concerned about side effects from Propecia other options include Minoxidil,Low Level Laser  therapy and/or PRP.I would recommend a thorough evaluation by a Dermatologist or experienced Hair Restoration surgeon in order to discuss your treatment options.

at this age with advanced degree of hair loss and limited donor hair availbale in your donor zone, it is a better idea to see an experienced hair transplant surgeon in person to see what your avaialble options are and also what your ecpe rations should realistically be. 

The use of 3500 grafts is more than adequate to treat the balding area shown in the photos you supplied

You are young and may be headed for Norwood Class 6 or even 7. Most men are born with approximately 100,000 hairs. In individuals with class 6 male pattern balding, they have already lost 60,000 hairs. Transplanting 4,000 follicular units is only replacing about 8,600 hairs. No one with that hair loss will ever gain full density. Please see a dermatologist to help you with medical therapies as your hair loss will be progressive.