Once you've set your location - just check back in with the app every few hours to update and sync your data. You won't get a green StreetPass light but you StreetPass compatible games and your plaza will probably have new StreetPass data - indicated by a green indicator!

iirc tag collecting is server side so you can turn off the console, just make sure to open netpass to claim the tags you can change the location every 10 hours

Oh, and you don't have to keep your 3DS turned on! You'll be in your selected location for 10 hours even if your system is off - just open the NetPass app when you next turn your system on :)

thank you everyone!