Storing..vintage Rum..

[rum_loving_viking]

Hello all

Hope some can help me.

Vintage rum, a rum that is 30-40 years old, is it still ok to drink? Sorry if my question is a bit "stupid", I am trying to learn.
I guess rum is the same as wine or other spirits, like Cognac.

Also, how is the best way to store rum? Dark and standing up?
How about after a bottle is open? How long is it still drinkable?

Thanks for helping me