1) Not sure about writing NTFS in linux but most major distrobutions can read it just fine.
2) FAT and FAT32 are both read/writable with nearly all distrobutions, just set the type to vfat in /etc/fstab and you're good to go.
3) It depends, in /etc/fstab you can mount it wherever, it'll just look like a directory. Say you do this
# mkdir /mnt/dos
# mount -t vfat /dev/hda1 /mnt/dos
Where DOS is on hard disk #1, partition #1, once you've done that then just ls /mnt/dos and you'll see your DOS partition