Ok well here is the info I have so far then once you get your codebreaker.
http://psx-scene.com/forums/424968-post14.html
If you want to read the whole thread, the link is at the top right, I just wanted to point you to the file you need.
Basically you are going to be able to launch
uLaunch 4.12
Read up on it, as it is basically a file management for the
PS2 and you are able to launch other elf files, move files etc.
So then once ule is running you will be able to install the Free_MCBoot 1.5 or 1.4 whichever you prefer.
Now you will also need the DVDELF.bin inside your BOOT folder along with the FREE_MCBOOT.ELF, so just download
my BOOT file, and it has it with it. But if you want the 1.4b then download it
from here.
So once the loader is installed, with it you will be able to copy the
ESR Beta file to your memory card, which allows you to boot backups on an unmodded
PS2.
The link to the whole Freevast forum is here, in case you need more info or help.
http://psx-scene.com/forums/freevast/
Now as for your other questions, yes you can use an
USB hdd on your Slim PS2 using
USbadvance.elf.
As for the transferring games to hdd, you only need to use the first app listed, USB Extreme Win32 utility
Not all games are compatible with the USB drive due to the 1.1 usb speed of the PS2 and due to the DNAS. They may require you to swap the DNAS or IOPROP, and rebuild the
ISO.
http://forums.afterdawn.com/thread_view.cfm/348187#2100927
If you still have your FAT PS2, you could get a hdd network adapter and use an
IDE hdd, which is more compatible.
You would just launch hddloader.elf off your mc
http://www.console-exploits.com/forums/showthread.php?t=9236
I think you can
FTP files like video, music, pictures etc.
But for games this method works, it is slow though.
http://www.console-exploits.com/forums/showthread.php?t=9708
Read this first to setup your ip address
http://ubergeek.awardspace.com/phpbb/viewtopic.php?t=5
You can find many
elf files here that you may need down the road and tutorials etc.
Good luck, let me know how it goes, and I hope I haven't confused you on anything. Its early here, so if I forgot anything let me know.
Anyway I gave this a go on my unmodded V5 PS2 using Codebreaker and it worked.