Private Vlan Isolate

I was thinking how private vlans would work within the enterprise networking settings. Let's say, a guest vlan X is configured as an isolated p-vlan, of the primary vlan Y. I curious as to how:

1) since isolated p-vlan are by interfaces, does that mean the AP can only allow that single vlan to traverse that interface?

2) how would DHCP addressing work? Would a DHCP server need to be on p-vlan X since p-vlan Y is the gateway and other community vlan cannot communicate with the DHCP server inside p-vlan X?

I'm not trying to implement this kind of configuration, merely understand the use of p-vlan within enterprise network.

Thanks!