Hi Ali, well as the proud possessor of nipplet which wowed my BCN today, here are my answers...
There are various techniques, from nipple sharing via skate-flaps star-flaps and t-flaps to free skin/fatflaps. I had the last of these as real nipple is too diddy to share and my PS won't do origami flaps on irradiated skin. Answers are based on my epxerience, which is much the same as the other flaps I believe.
1) No, not at all... it is done under local and takes about an hour.
2) None. Well as long as it takes for the local to wear off. May be a litlte bit sore depending where they take it from, but nothing otc pain meds won't fix. I wnet out for coffee and cake afterwards, then back to work.
3) I wondered that too... but I trust my PS. She told me that symmetry would be slightly off as she was working with the centre of the 'patch' in my recon (where the areola used to be) and my uplifted boob has not yet re-drooped. Tbh it is only out by a few mm so not far off what nature supplied. Five weeks on it has settled and looks amazing (my BCN was convinced it was a nipple share!).
Sizewise, the finished article is very simlar to the real one in terms of diameter, and in terms of projection I suppose about the same as semi-erect

(vicars probably aren't meant to know that, especially single ones!!).
Couple of thoughts...
Have you tried a prosthetic nipple? I haven't had one, but they come in all shapes and sizes, and would help you decide if it might be for you. My hosp will even custom make these by moulding from the remaining real one!!
Have you seen any photos of his work? Or would he let you speak to any of his patients? Most PS seem photo obsessed (well mine is anyway) so it may be feasible to see some pics.
PM me if you have further questions... I was very dubious about getting this done but am absolutely thrilled with it, and it has given me loads more confidence!