drdimento,
1. While partitions can be changed later it might be favorable not to do so to avoid putting one's data at risk (espcially for those of us who avoid the "pucker" zone) and thus, one should chose the partition "quantity" wisely in the beginning.
Well, I am going to recommend that you use Time Machine. Doing so will require a bit more of that external storage, but it will entirely remove the "pucker factor" that might otherwise be involved in re-sizing partitions. Trust me, Time Machine rocks (I recently formatted my internal drive, then restored from TM; I was able to restore my 100 GB+ installation of OS X in about 45 minutes, using a Firewire 800 external)! I've had great success dynamically re-sizing partitions without affecting my OS X installation, but having a good Time Machine backup makes the possibility of even a catastrophic failure in this regard... no big deal.
2. It appears FCP projects can be stored on an external drive without having to save space for FCP projects; and, FCP Suite 2 consumes approximately 45 to 47 Gb of space including its' templates and additional materials.
All true, but those "templates and additional materials" can be, and often are, stored on an external. That's what I recommend you do. In fact, I believe that most video pros who happen to be using a portable store those files externally.
3. The OS X Leporad uses about 22 Gb of space.
The
what??? (LOL) Leopard can be squeezed into 22 GBs, but it's not pretty. If I am not mistaken, just Garageband (along with its "additional" files) consumes something over 7 GBs. See my last post.
4. Mac and Windows files can be transferred across the platform via the external FAT32 drive(s) and while USB 2.0 will work favorably for FCP and Garage Band files, the preferrable drive would be a IEEE1394-800.
As others have already stated, your best bet might be Macfuse and/or Macdrive (within OS X and Windows, respectively). HFS+ (the native Mac OS format) is, without doubt, the best format for storage of your media files. My only concern would be its compatibility, even if you use Macdrive in Windows, with Avid. You might want to look into this on both the Avid and Macdrive support sites.
Barring the workability of HFS+ and something like Macdrive, or sticking with NTFS and using Macfuse to be able to write to that format in OS X (OS X will read NTFS, but cannot natively write to it), FAT-32 is the only option for bi-directional portability. The biggest drawback to using FAT-32 is that it has an inherent 4 GB file size limit.
I have had a look at your "profile" for the forums, and it does appear that you aren't just a "hobbyist," but will be using this machine in a serious way. I know that you are "portable shopping" right now, but have you considered that what you
really need is a Mac Pro?
Scott