I have a VR-400 and the WiFi connection is weak and can't support all devices all around the house.

Want to but an additional Deco M5. 

1. Can those two work together? Does the VR-400 should be switched to modem only mode? or the M5 will be wireless router only?

2. I have a CAT-5 (?) cable running all the way to the bedroom, so one of the units will be connected to the main modem/router and to this cable, and a 2nd unit will be connected to the 1st unit by WIRE. The 3rd unit will be wirelessy. 

3. I need the VR-400 to still enables all 4 lan ports (TV, XBox, etc... are wired connected to it, with static IP for all of them).