I am running Windows' cryptonite-qt.exe wallet, would it help the network if I leave it running?
Yes it will help by validating blocks and helping other peers to sync. Better if inbound access is enabled by opening the port on the router or enabling UPNP (must be enabled on the router as well, it might be by default).
OK I will let it run. How do I check if my UPNP is enabled? Sorry I am not tech savvy.
First enable it on the wallet preferences.
Then wait some minutes (better some tens) and run "getmininginfo" on the console.
If you see some nodes with "inbound: true", that means you are receiving connections from the outside.