FF will do a bit better at high ISO
It's not "a bit" if we're talking about same sensor tech with different size of sensor. Difference is very significant. That's why reportage shooters never use APS-C. Situation with lack of light would make shooting on APS-C with decent quality nearly impossible.
It depends. If you need to stop down for sufficient depth of field to keep your subject in focus, then APS-C has the same low light performance as full frame.
Full frame has the low light advantage only when you select shallower depth of field than you can get with APS-C.
It's clearly that you didn't shot at night much. I'm into night street photography for more than 10 years. Let me tell you something. When you're - for an example at f8, difference on APS-C and FF depth of field would be nearly invisible, while you still get much better ISO perfomance. Also, even if you shoot with narrow depth of field you still ABLE to shoot at high ISOs, even if it 1.4 or 2.8, while on APS-C, yes, you'd get wider depth of field, but you'd still won't be able to shoot due to very high level of noise. it's not like "I gonna get better images with a fullframe", NO. It's rather - "if I gonna make a shot at all or not". And wider depth of field on APS-C is not that wider as how much ISO on FF is better. So, it's not about whether APS-C or fullframe is better. It's all about the ability to get the shot or get nothing, and who cares at this point whether it would be narrow depth of field on 1.4 on FF or it wouldn't - while the picture would be taken, and would be taken in DECENT image quality with ability to post-process shot, because on modern FF even at high ISOs - DR is still pretty nice. At this point, in such types of photography - nobody cares how narrow would be depth of field, because it's not about depth of field at all. It's literally only about ability to take the shot itself. With FF you go home with a nice pictures, and with APS-C you going home with a noisy mess. It's what night street photography is. I bet, reportage shooters, who're working in the field a lot and shooting at night can tell you completely same things.