The first is an inversor amplifier that has the transfer function is: Vo/Vi = -R/R. In this case it works like a inversor buffer.
The second is just a buffer ...
Both has a stability because of negative feedback, but it's stability is determined by internal feedback compesation capacitor, in this case (G= 1) the feedback is very nearly of -180º margin fase that can be non-stable if you introduce capacitive loads....
The cut frequency is determinated by bandwith frequency of amplifier
remember: const = W*GAIN
if GAIN = 1, then -3dB is just W of amplifier.
leomecma