hostap iapp and dhcp question

[David Goodenough]

If I have a set of wireless access points running hostap and I enable
802.11f with iapp_interface=eth0.  I want these to appear to be a seamless
single network to the users.

Should I be running one dhcp server (or one server with a relay on each 
access point) to handle all the access points, or should I have one per access 
point?

In either case is there any communication between hostap and dhcpd
to hand over address allocation?

In the case of a single dhcp server how is routing handled, other than 
bridging the whole network?

Also the docs make reference to an ESS (Extended Service Set).  How do I 
set membership of such a set, is it as simple as using the same ESSID?

David