Do not do not do not do not pluck during your laser treatment.
Some blond hairs have dark roots and can be affected. Some hairs will LOOK light, but you will pluck some dark ones accidentally. Further, if you're plucking stray dark hairs, it's just dumb - you can't kill it with laser then.
I've had black and red hairs removed by laser, but blond hair does persist. I have some hairs on my upper lip that are black but immune to lasering. I've had around 11 full face laser treatments and a couple of spot treatments on areas (upper lip, 15 times yet I still have some dark hairs there.) My sideburns aren't even, but I'll worry about that later on. I've had a trial session of electrolysis, and Saturday I go in for a full treatment. I'm hoping it'll only take a couple of hours for the majority of the hairs. It's *hell* to let my face grow for the week it takes after laser+hormones to grow an appreciable length, but a good length makes it easier to zap.
Laser is usually paid for by area, if they are letting you block time instead, then absolutely tough through the pain and let them work on as much as they can. You should probably use it for chest and underarms as priority... sometimes you still need your chest done after hormones, and under arms are just DIVINE to get rid of. If you have bad shoulder/back/neck hair, though, I'm not sure how much HRT affects that...
Laser really cleared my face up, I'm afraid of what electrolysis will do since it does cause you to break out. That, plus having to stop shaving, sounds really obnoxious :/