USB can handle 127 daisy chained items. However, there's like an absolute maximum of the amount of data and power that can go over any one USB port.

Assuming this is USB 3, that would typically be capped somewhere around 5 gigabits per second and usually, 5 to 15 watts of power, so they would all have to divvy up that between themselves.

USB is pretty smart, so it probably won't automatically divide down based on the number of attached items like Wifi used to and instead the controllers should dole out the in-out requests on an as needed basis.

Not really, it depends on what each device is doing. There is a shared aggregate bandwidth to draw from. It’s not a 50/50 type of thing