Firewire drive formatting - NTFS or FAT32?

Use FAT32. You should be able to format the drive with Disk Utility. Mac OS X only supports reading of NTFS volumes, not writing, which limits the usage a bit.

Basically, NTFS can be faster than FAT32, supports more security features of Windows NT/2K/XP, can be more space efficient, can be more robust and is journaled like HFS+.

Another choice is to format the drive in the usual HFS+ way, and get a copy of MacOpener for the Windows system. It allows Windows to mount Mac drives. I haven't used it, but I've heard good things from people who do.

Sorry I don't know, I prefer to keep my drives with one large partition it makes managing what computer can access what files a lot simpler.

> What about two partitions, one small FAT32 to mount on PCs and the other a large HTFS+.

You cannot mix the two partition schemes.

> I hear OSX likes all partitions to formatted the same way.

Do not mistake the partion scheme for the actual partitions. The former is rather similar to a table of contents while the latter would be the chapters and text, proper - that's why you can't have two different [incompatible] TOC formats simultaneously.

> What will happen if I do this?

The operating system is slower at reading non-native partitions anyway.