Networking help!

I am working on networking two buildings. Building number 1 is where the DSL comes in. I have a Wireless router in this building. The two building are connected by network cable. In building two, I need to setup a wireless connection for that building to use. Should I install another router in building 2? or can I just use wireless access points and plug them into existing wall jacks? Any help is appreciated.

One more question, can a cat6 keystone be used with cat5 or cat5e cable?

Thanks!