I was circumcised at 12 years old as I had a tight foreskin that I couldn't pull back (also known as phimosis). It's hard for me to comment on loss of sensitivity as I never really experienced my "uncut form", plus I obviously wasn't sexually active at that age apart from masturbation. I love the look of my circumcised dick now, my glans has a nice pronounced ridge which seems to be a hit with my partners. I also have minimal scarring and like the "clean" look.
I'm 38 now and in regard to your questions, my cock is perfectly sensitive enough for me. With this in mind, I like a really hard grip on my cock when jerking off/being jerked off and find it really difficult to cum without it. Perhaps it's a result of the circumcision, but I only know what works for me. The head of my cock still feels sensitive against clothing and sex is no problem. I last a decent amount of time and it always feels good, so maybe I don't want to be more sensitive!
My only regret with getting circumcised is that I wish I'd known what it was like to have a foreskin. They turn me on and look fun to play with, so I feel like I've missed out in that regard.