Did I interpret these multisim results correctly?
Was I able to adjust the signal level properly to get an output of 5
Vp-p?

No. You have probed circuit output properly. It shows a voltage amplitude of 28.2V peak-to-peak. However, this measurement is not to be trusted. Had you actually looked at the waveform, it would not be sinusoidal. It would look more like a square wave: when you apply a sine wave at amplifier input, you should see a sinusoidal wave shape at amplifier output.
A too-large input signal asks of the amplifier to generate an output amplitude that exceeds its DC supply voltages. Since your DC supply range is 30V, that 28.2V p-p output signal is limited to a little less than this range (output can only approach, not exceed DC supply).

Is the V(gain_AC) shown by the probe, the actual gain of the circuit?

No
As stated above, a sine wave applied should yield a sinusoidal wave at amplifier output. This amplifier is driven with an input amplitude that is too high. A lower input amplitude should be set on the function generator. Set it low enough so that output amplitude eventually drops to 5V p-p.
As a check, if you reduce input amplitude in half, output amplitude should also reduce by half - this check indicates that the amplifier is running linearly.

In the AC sweep I did, is the value I highlighted the upper cut-off frequency and the bandwidth?

Your method seems correct. Once you get the amplifier running linearly, do this again - you'll likely get a different result.