I have a question about using the action from a Holding on another province than the one under attack. Say for instance that I have Imperial Storehouse, can I sacrifice it to gain a card draw even if it is not on the province under attack. I would think that I could as I know you can use actions from characters outside of the current conflict.

Yes you can, you can even use this action during dynasty phase. Unless the ability cleary states when you need to use it you can use it during any action window.

Presence doesn't exist in this game. Unless the card specifies that it needs to be attacking or defending or something similar, presence shouldn't matter.