I think that's correct. Freihung is close by, but for some reason you can't buy those tickets online? Weiden is the next closest non-artarded route.
Looks like I'll have to taxi to Weiden, the take the RE to Nuremberg. I think that's correct.
Yeah, that seems like your best bet. Seems like the trains from Nuremberg to Weiden run for a long time.
Also, tickets not being available online usually either means that it's a bus where you have to pay at entry or that it's a train that's run privately, where you usually have to buy from a machine at the station. Neither should scare you, just have some coins ready.