4. When node complete (should take 2-3 days), if I shut down, will Node still be in place (will it update blockchain from where left off).
5. What can we do with Node? Any advantage for newbie or are we just helping the network in the background
Yes, if a node goes down and starts back up, it will sync the blockchain from where it left off.
More nodes are always better to decentralize the Bitcoin network, but I think you should be able to run "Apps" on the controller as well.