[mrmistoffelees]

Don't attach another router to the HH !!

By default you will end up performing double NAT or potentially treble NAT if carrier grade NAT is in operation.

Replace the HH

If you want to do it properly I'd suggest the following

purchase a 2nd ADSL connection
purchase something like an Netscreen SSG5 and use virtual routing to forward guest traffic over one ADSL circuit and your own traffic over the other.
purchase seperate AP's and install in the building(s)

I'd be quite prepared to come and set this up for you if you wish