Best range for 6 wireless access points??

I have a house that has 16 rooms, approx 20,000 square feet, 2 floors, it has ethernet in wired into 6 of the rooms. There is a main rack in the centre of the house on the ground floor with the broadband coming in through BT ADSL. The walls in the house are very thick.*

I have already tried Devolo homeplugs and they are not working very good. So have decided wireless access points are the way to go.

The router is a Netgear DGND3700 attached to a netgear 8 port gigabit switch. There are 6 wired ethernet connections that are going straight into the switch and then into 6 of the rooms around the house.

I would like to have a single wireless network covering the whole house and garden area.*

Whats the best way of setting this up so that im using using all the wired connections going into the 6 rooms?

Also I was looking at using the netgear WNDRMAC routers as access points, but im not sure now. I would appreciate it if anyone has a better solution?

I also have a single wireless printer that needs to be connected to the wireless access points. I have pc's, macs, iphones, ipads that need to be able to print from.

Im not entirely sure how to wire this all up?

Thanks Guys!