you will require minimum 600 MB of disk space for minimal installation and up to 5 GB for full installation.
HFS+ and HFS are the standard volume formats for Mac OS X.
RH EL supports ext2,ext3,lvm,swap,software RAID and vfat
if you want for support for HFS+ you can download the HFS driver patch for your kernel version. you can get the patch for 2.4.x kernel from the following link
http://sourceforge.net/projects/linux-hfsplus
i suggest to use ext3 file system.