Re: 1.
Yes that is possible
Re: 2
Sysinstall will only touch those slices, you tell it to touch.
Remember that each FreeBSD slice has it's own disklabel. Your "/etc/fstab", which contain the instructions for 'mount" will thus look something like this:
Code:
/dev/ad0s1a / bla,bla,bla
/dev/ad0s2d /home bla,bla,bla