The more im reading the more appealing this is beginning to sound. Ive seen a few different ways to Root and install SuperUser, which one is the safest/best? There are still alot of things i need to cover, i want to get my head around the whole process before i do it as i dont really fancy a samsung paperweight
If i install a custom ROM (which i very much intend to do) will it overwrite all of my apps? Im speaking specifically about the camera app, i quite like samsungs camera app but will a custom Rom overwrite my camera software?
That depends on what rom you flash. There are basically we kinds of roms for the S4, Touch wiz based roms, and Aosp roms. Touch wiz roms are roms built off of your phones stock software. The software made my Samsung for the S4. If you flash one of these you will keep your TW camera and gallery and all of the touch wiz features you probably bought your S4 to get. Like the smart stay, smart scroll, all that stuff. Like i said they are based off of Samsung's modified a Android software, just modified to add more features and remove the junk apps you don't need like all the Verizon apps and some if samsungs dumb apps like media hub. In my opinion Touch wiz roms are the way to go with the Galaxy S4 (and s3 too for that matter) they are made for this phone. Just better than factory stock. Roms like Jellybeans, Cleanrom, and Hyperdrive are tw roms. They will have the normal camera you prefer. Personally I would recommend Jellybeans.
AOSP roms are just Android "the way Google meant it to be". It's alot cleaner of an interface, with less junk. But you miss out on samsungs cool features. Roms like the legendary Cyanogenmod are made from this. Look it up on YouTube and you will see what i mean.
There is alot of debate on what people prefer. But personally I prefer Touch wiz. AOSP generally has lots of bugs and other small issues, but it is still Cool. Just not my preference for this specific device.
The root method I would recommend is here:
[TOOL](ROOT)(RECOVERY) i545 all-in-one root + recovery installer Updated 6-3-13 - xda-developers
This is the easiest way. Just follows the directions and it's a piece of cake. Make sure you read the thread THOROUGHLY before attempting so have an idea how it works. If you just follow then instructions you can't mess it up and it literally takes five minutes. When your done you will be ready to flash a rom. This method doesn't actually unlock the bootloader of you device (which you must do to flash custom software) but it's a work around. It gets us around the bootloader to be able to flash roms. Eventually when developers figure out a true unlock method this procedure will change. But for now, it's easy and works fine.
I would recommend downloading a factory image just to keep on your computer at all times just in case you get into hot water, so you can always flash back to stock if something goes wrong. Follow this thread:
xda-developers
Oh yeah, to answer your other question, when you root yoy won't lose your apps, but before flashing a rom you will have to wipe your phone and make you lose your apps and everything. Before flashing a rom, download titanium backup from the play store and back up all your user apps. Once you flash the rom, just restore them with titanium and voila, you have all your apps back WITH all the app data intact. So you will keep all your angry birds levels. Lol. Titanium backup is THE BEST root app ever made in my opinion. A rom flashers best friend.
Well I think that's all the info you asked for. Hope I helped!