How effective / successful are hair restoration procedures for men (planting hair in the scalp, etc.)? Won't the hair just fall back out later?

Very successful. Hair transplants work well. Consult someone who specializes in follicle or micro hair transplants as these work best and give the most natural hair line. The transplanted hair will fall out but if done properly a new hair will regrow from this area.
Very effective. When done by a qualified physician. As you probably have noticed, even someone with severe pattern baldness has some hair which never falls out at the back of the head. This is the hair which can be transplanted to the top of the head. It will continue to grow normally. The expected results are based on your age, pattern of baldness, and other factors. Seek a qualified hair transplant surgeon.
Very, if you're . Willing and able to pay for as many sessions as is necessary. Ave =3? Transplants are living autografts so should not fall out.
Works well. Hair transplantation is very effective when done properly, and the "new" hair is permanent - it will not fall out if it was done well and the hair was harvested from a health donor site. But it needs to be done properly, by someone who does lots of them, not one a month at a nationwide "chain." find someone with a transplant that looks great, and ask him who did his.