My teacher said to connect CD+ on the ULN's to the +12 I'll be supplying the 7-segs so that when the ATMega goes low, it'll supply them with the +12 they need to work, instead of the +5 supplied by the chip. Is this not how they work?
I tried having A0 - A5 connected to ground like digital inputs, but I was getting really screw results while breadboarding. The switches were closing unreliably, just by tapping or getting close to the actual wires without having to actually press the buttons. Once I put the resistors in, that solved all my problems.