I'm thinking of upgrading my piffling 40GB HDD in preparation for GT5 later this year, and I've bought the replacement HDD (500GB no less

), but before I proceed I just want to make sure a few things first.
Oddly, my new HDD doesn't measure 2.5 inch across, but the store says it is

It's ~4.6 inch across. Will it fit? Also, I can only find a 5400 rpm one, is there that much difference in performance compared to a 7200 rpm one? In terms of load times, how many seconds shorter (approximately) are we expecting?
I also plan to use my 80GB iPod as the external backup HDD, will this work? I've read somewhere that it needs to be FAT32 formatted, is that correct?
Third, I REALLY want to make sure none of my data are lost, so if anyone with a kind soul is willing to help, could you give the following list a check?
Game data (including updates, patches, etc)
Game saves (including locked ones)
Trophies (do I have to sign-in to PSN first to 'reclaim' them?)
User Info (everything under Account Management)
DLCs & DLGs (i.e. PSN downloaded games)
Themes & Avatars (especially premium ones)
Users (the ones when you first start up)
F@H data (records, my current project, team details, etc)
Friends list (self-explanatory)
Settings (basically PS3 settings e.g. display, sound, system patches, etc)
Also, I've read that when signing-in to PSN for the first time you need to select 'Add Existing Account' instead of the other option. Is this correct?
Sorry if I'm being overly OCD lol. My GT1 & GT2 gamesave got corrupted once many years ago and since then I'm extremely paranoid when it comes to backing up/transferring game data and stuff

I also realize that most of the stuff I asked could be re-downloaded from PSN, but I have a very limited internet quota so it would be more convenient for me if I don't have to.
Thanks in advance 👍