Does anyone know if acupressure / acupuncture works for pinched nerve pains?

Arthritis. It can, but first get clearance from your doctor who can also make the referral if he/she deems necessary.
Well... Most acute (recent) disc herniations causing a pinched nerve get better over the course of a month on its own without anything. To my knowledge there is no scientific literature to prove acupuncture is better than placebo for pinched nerves or for low back pain. That being said, acupuncture may be very relaxing and generally not associated with too much risk. (i think). Hope your pain improves!
Yes. Acupuncture can be very beneficial for this source of pain. However, if surgical intervention is required - then the pain is likey to continue to recur over time.