linux partitions: swap partition is definately advisable. perhaps 2x your ram capacity. the rest is up to you. there are advantages to using separate partition for boot or usr or home or var ... but it is not necessary. check out some of the howtos for more details http://www.linuxdoc.org/
ext3 is the same as ext2 but with a journal added. basically, if you power off your linux box (not a clean shutdown), you will not have any corrupt files (in theory). i have found that it works well on the 4 systems i have that use ext3.
GRUB is newer and seems to be more stable then LILO. it wouldn't hurt to do some research and deside for yourself.