[ubuntu] Virtual Box Image of Ubuntu (Guest) on windows 8 (host, 64 bit)

Hi,
I am trying to install Ubuntu (Guest) as virtual machine on Windows 8 (Host). I need some clarifications for installation.

Can I install Virtual Box Image(32 bit ) of Ubuntu (Guest) on windows 8 (host, 64 bit) or only Virtual Box Image(64 bit) of Ubuntu (Guest) has to be used?
Shall I need to use images of Ubuntu provided by Virtual box only or can I use images provided by Ubuntu
What difference does it make with installation using VmWare?

Thanks,
Satish