AirPort Extreme 5G and a DD-WRT Router ----Safe?

Yesterday I got AirPort Extreme 5th Generation which replace our broken Linksys 310N v2 router which would drop the signal almost all the time and pist us off for the last 3-4months. Ya can use it as a hub if ya like bc the wifi part never likes to stay up long at all.

We have another router (Linksys 300N 2 anttenas sticking out) upstairs in my parrents room for there BR-DVD Player to stream Netflix, pandora, and a whole lot others but mostly Netflix is runn'n up there connected to our Linksys router on the main floor.

---I was wondering is it safe for a dd-wrt wirelessly to connect with the AirPort Exetreme 5G? I'm good at routers n such but im new with AirPort.

Sometime in the next couple months or so, i be probably getting that replace too so that be replace with the AirPort Express. and i here it can connect to other Airport's right?

----if safe, Any good sites for a dd-wrt connecting correctly with a AirPort Extreme?

Before any1 of you ask, I got the Extreme bc of the specs and mostly bc of the 3 ports it has for our Xbox 360 (2006), DirectTV HD Demand, and my parrents PC, other than the ports are gigs so thats good to. (LAN-LINE) wich we're replacing our ethernet cords bc the safty satch are broken and so they get loose and ya kno! 😀