I think that, at least initially, just having a single chest that could be accessed from any dig spot would be okay (not realistic, but you can access all your ships from any island, so it pretty much fits with their sense of reality
).
Hadn't really thought about transferring money with it; I suspect they're not allowing an easy option because of what has happened on some other MMO's (where people pay real money for gold). I do think it should be a lot easier to transfer money between pirates on the same account, though.