The laser & extraction cost me $800au. the other costs (hospital, etc) totalled about $1,500. i had it done in Sydney which is quite expensive, so i'm not sure if that will be any good to you.
i got the same "no idea what it is/just deal with it" speech from dermatologists, and it took me forever to find one that had treated the condition before. but definitely make sure they have done it before and that you have confidence in them because there are so many things that can go wrong with even the simplest laser surgery. and the last thing you want is to end up with a raised scar on your lip. about the lasers, there may be new lasers that produce the same effect, so i'd ask to compare them to the CO2. oh, and if possible, ask for any before/after photos. actually, ask as many questions as you can because i didn't, and i really wish i had.
the spots that came back were both old and new. the most visible are the ones around the corners of my lip, they're very small and hard to extract. the newer spots seemed to appear after i had healed. so i guess whatever caused them in the first place was still causing more. the last post i said 70% were gone, it's more like 30 - 40% now to be honest.
also, the spots seemed to vary in size as they returned. and they still came back in clusters causing that discolourated look on my lips.
your last question, i can't answer. i forgot to ask the spot size because i felt so confident in the doctors. however, they didn't apply any cream in between and they passed over many times with the laser. the deeper the spots, the more passes. and unfortunately, the more passes, the more chance of scarring. which, despite the fact that i was told scarring would be "extremely rare in this case" i've noticed a small, raised area on my lower lip that was not caused be anything else. thankfully it's not that bad, but it's still going to take about 2 years to fully heal apparently.
looking back, i probably shouldn't have had any laser treatment at all. but i'm not the type of person to just sit back and do nothing, so F it.
anyway, i hope that helped a bit. and i wish you the best of luck!