From what I understand.
Q1
yes it would bleed but only if there is already sufficient coolant in the radiator to fill the space when expanded "swells". So only if there is only a slight amount of air.
Q2
No. The expansion tank will only allow coolant into the rad when the coolant "shrinks" to fill the space created.
If you have a leak it creates a point where the coolant can expand rather than shrink.
Like when you radiator is hot and you get some numpty take the cap off. It goes everywhere very fast as it swells.
Eventually the level will drop and drain the exansion tank if it's a slow leak or closes when cold. But a large leak you will hopefully notice very quickly through coolant temp and steam loss.
Q3.
Just different systems.
1 uses rad cap to vent on overpressure and allow air to escape from expansion tank.
Other will normally have an expansion tank cap that can vent when hugely positive but also uses the head of pressure to control amount in the rad.
They aren't thermostatic caps. They are pressure. Pressure and temp in these circumstances have a fairly linear relationship.