[ubuntu] About share folders and remote access

Hi all,

host - Ubuntu 12.04 desktop 64bit
guests - all 64bit Ubuntu 12.04/Debian 6.0/Windows Server 2008/Windows7/Windows8 etc.
Virtualizer - VirtualBox

1)
Would be be possible to share folders/directories between Linux<->Linux, Linux<->Windows, Windows<->Windows guests? If YES, pls advise how.

2)
How to setup remote access Linux<->Windows and Windows<->Windows guests?

TIA

satimis