To find the age of Pietta guns you would need to know the model and serial number, The blue book of modern black powder values has a section in the back listing manufacture dates based on this. Or let me know the info and I can give you the year made.
Take it to a gunsmith. That is what they do.
Try Proofhouse.com
Impossible to answer without a DETAILED description of ALL markings.
I might be able to help if you would be willing to tell me what IT is.
You will have to tell us if you are talking about black powder or center fire.
By comparing markings and workmanship to a known original (and to known reproductions). A certain sign of a modern reproduction is the marking "Black Powder Only"- since at the time the originals were made, there was ONLY black powder.
.32 cal. black powder
I suppose you mean in powder form, Henna is never black so you won`t be able to buy it as a powder. People mix Henna with chemicals to get "black henna" which is very harmful and should not be put on skin. Sometimes people sell Indigo for hair and call it black henna but that is nonsense, you cannot use Indigo all by itself to achieve a black colour. You won`t find black henna powder anywhere, so there`s no need to be worried about that.
You will have to call TC to find out.
Contact your local sherrif , he /she will be able to tell you. If you do not have a violent felony, I would guess, yes.
Am unfamiliar with which of the states MAY allow this, but I can tell you that the FEDERAL LAW (USC Title 18) governing convicted felons and firearms possession specifically names and describes black powder arms as firearms - which are prohibited to convicted felons.
Call Colt and they will tell you. Proofhouse.com has Colt sn data.