So how do I remotely connect to my own (private) node which I run at home using Monero Wallet GUI or any capable mobile wallet app for that matter? Is it just a matter of using my external (WAN) IP address and port 18081 then? If so, how do I pick which node to connect to if more than one node are running at home either (for the sake of argument):
1. more than one monerod instances in a single machine (not sure if this is even possible - haven't tried it), or
2. a monerod instance in each of more than one machine (most likely)?
What are the possible privacy/traceability scenarios in employing the above method (remotely connecting to my own node that I control)?
You need to set up your router to port forward to the machine that you want to connect to. You also need to allow your daemon to accept remote connects (I think by default it only accepts connections from localhost). I don't think there are any privacy implications.