1)I think you are contradicting yourself. If deaging did occur then most jobs would be very difficult to manage.Sharon Vineyard was able to get away with it because of very clever use of disguises. So either he is somebody with a lot money and somebody is acting as a front for him or no deaging has occurred at all. I don't think you deal with math teachers who has taught two generations of students without ageing. tThe lsame logic can be generalised for most professions. Therefore being a chronologically old man with a lot of money is the only possibility(I am assuming Gosho would not throw in something like a board directing the organisation and anokata only represents the boards' will in which case there is almost nothing to go on) if we were to assume he is a deaged person. If not then also the most probable profession of the boss would be that of an old businessman because of the reasons mentioned by the creator of the thread. Of course if we were to believe that there have been more than bosses then the board theory would gain support because there has to be some appointing body.
2)at the end of the off season valentines party case vermouth got a mail from the boss calling her back to his side. From this i think it is safe to assume that vermouth has met the boss. Assuming that vermouth and gin are equally ranked it is quite possible gin has met the boss.
3) I had a question. I am fairly new to DC which perhaps would be evident from what I have wriiten above. Why do you people always assume that vermouth has hidden the identity of Conan Edogawa. He is a child in his current form, has almost no leads to go on and perhaps because of his association with kogorou mouri and so many police officers eliminating him and perhaps even mouri would not be very safe because if it is a detective they are dealing with he perhaps would have already designed someway to transmit his investigation to his trusted people(in this case they are dangerous because the list includes heiji hattori who's father is a police chief and a person who is the mycroft equivalent to shinichi yusaku kudo) in which case killing a silver bullet may lead to the production of three more silver bullets. This theory also holds ground because yusaku does not frequent Japan that often even after the shrinking of his son and you don't want to eliminate a great detective to get the best against you right? Further the reason why the boss hasn't asked vermouth to reveal this to the organisation is because he knows gin well. We saw in that Valentine's Day case that gin ordered vodka to not hold back even against vermouth which mean he takes charge in a lot of situations. Thus in accordance with the cautious behaviour of the boss it is his best alternative to keep shinichi alive in my opinion.
PS: I apologise in advance for any grammatical or plot related error I made in the above banter.