Also, I'm stopping over in Bamberg for just one night and leaving towards Nuremberg the day after, is there a way to get a ticket that would cover both?
Yes, by cleverly choosing your departure times for a ticket from Berlin to Nuremberg and specifying a stopover in Bamberg for 18 hours. I see you could buy a ticket for today like this:
Sept 24, iCE 705 dep Berlin Hbf 11:37 arr Bamberg 14:15, Sept 25, RE 49 dep Bamberg 8:38 arr Nuremberg 9:19
Supersparpreis 46,90 €
And sla019 suggestion for a VGN day ticket is worth investigating. That way, you can use all the local transport in Nuremberg for the rest of the day. You could get a 7:37 departure from Berlin to Bamberg for 35.90 EUR Supersparpreis. A VGN Tages Ticket Plus would cover all public transportation in the region for the whole weekend for 21.50 EUR. So that would cover all day in Bamberg, train Sunday to Nuremberg and public transport in Nuremberg for the rest of the day Sunday.