[Samsung Infuse 4G] Dani897:
the difference is in the software an the lack of an att logo on the screen. the rogers infuse is internally identical to the att infuse, it can likely support mhl with an att stock rom installed through odin... the differences are in the param.lfs file (the boot logo is in there) the boot loaders, (you already have gingerbread compatible bootoloaders, no need to ever flash new ones, the kernel and the /system files.

what you have is a stock rogers infuse (rogers used the galaxy s branding, att did not, doesn't change anything) with an att baseband installed. ux is the carrier designation samsung uses for rogers, uc is att. lb3 is the latest official att gingerbread build kg3 is the only existing rogers build (broken down as year>month>build number of that month).

i don't know what you mean about "short term memory loss at all. are you saying apps are dissapearing??? or just that apps you left running are getting reset? or what? please explain. maybe you are using too much ram, maybe you just aren't communicating well... as far as stuff remaining after a wipe, well it is true a factory rest doesn't cear the sdcard outside of the sd-ext folder which holds apps. titanium backup keeps things backed up to the sdcard where they are normally safe (cept for a wipe through settings>security which wipes the sdcard as well.) and i don't know what else you might think doesn't belong.

when you open root you are in root is the best i can explain it. the linux file tree structure is very flexible and that also makes it not so strait forward. there are several paritions the phone uses, the aosp structure is different from the samsung structure so patitions are used for different purposes to some extent. where the os files are stored, except for the kernel is the system partition which is mounted as "/system" when you open "/" or root you will see a bunch of stuff, some of these are mount points for partitions such as system, efs, data, sdcard,... and some of what you see are mount points for, or symlinks to, important files that are actually contained in other places like ramdisks or within /system so there is a lot of stuff that is recursive. i haven't investigated to give better details on how exactly that works or what device is "/" known as to the operating system.

as far as getting to ics or jb you need to first flash a cwm kernel (unless you already have one, sounds like you may since you have an att modem on there. boot into recovery and check it out.). if you don't have cwm then use odin, heimdall or SGSkernel flasher. if you have superuser then sgs kernel flasher is the easiest bet and without a tethered connection there is one less point of failure. it's dead reliable. heimdall is reliable too but only as reliable as your data cable and usb controller... you can use an att compatible kernel (they are really rogers kernels with changes for att) for this purpose but even the "comunity" kernel or rogers root kernel should be fine as old as they are.

then you need to flash ics twice. the first time will give you the kernel with cwm v5 or v6 then format the /system /data /cache and wipe dalvik cache and flash ics again. then if you wish to upgrade to jb you can but you must be on ics first because of the cwm version and the mtd conversion, things will likely go wrong if you flash jb from gb. read the cm9 first posts, then read the cm10 and othe jb threads.