Does Windows 7 64 Bit Support 32 Bit Still

I have some questions about windows 7 OS.

1) Does windows 7 64 bit support 32 bit still?

2) Can I use windows 64 bit with 4 modules of ddr3?

3) Can windows 7 64 bit configure 32 bit memory channels?

4) Can I expect windows 7 64 bit to configure 128 bit width memory on dual channels 4 modules, or 256 bit width on dual channel 4 modules? (32 bit x 4 ddr3 modules)

5) Do I need to get a windows 7 64 bit + 32 bit OS package to use both 32 bit and 64 bit width memory configure?

7) Can windows run in 64 bit mode while use 32 bit architecture?

8) Can windows 7 64 bit be restricted to 32 bit when needed? or will I need a package that has suport for both 32 bit and 64 bit?

I'm asking because most all games I check on play with 32 bit os and only need 64 bit for DX11 graphics. I think one OS that can run both 32 and 64 bit with a click or switch users could be what I am looking for.