What direction to go with my core install?

I want to set up a simple VM server on my home pc. 

I want to be able to ssh or vpn in

I basically want it to be a centralized file server that I can access from anywhere, but also have access to from my local network.

I have a 2 tb external drive I want to use as my main place of storage - running on an older but steady laptop with enough processing power and ram to accomplish this. It basically sits there unless my wife wants to browse the internet.

Is there a way to mount the external drive to the server as well as have it available locally?  Would I map network drives to each pc locally and that's how I'd access info?

Should I go with the file server, or domanin contrller, or something else?

I like to play around and learn so the least limitations would be best, but obviously my needs aren't very robust. 

I currently have installed the turnkey core 12.0 and thought that I would add appliances on top, then I started seeing the appliances actually come with the core so if there's a way for me to just add the file server appliance on top of my existing install that I have up and functioning that would be cool. I would imagine there has to be otherwise everyone is pigeon-holed into their initial installation with no options. 

Newb to turnkey - there seems to be a lot of scattered documentation - although good forum help from the devs so figured I'd come here. Plus the vast amount of options leaves me wondering which direction I should take this.

Thanks to all!