[Q] New ROMs stuck at splash screen using SafeStrap topic

I have an unlocked AT&T Samsung Galaxy S4 and have been trying to use SafeStrap to flash new ROMs. Everything goes like normal, ROM looks to be successfully installed. But I have tried to flash three different ROMs that are compatible with SafeStrap and my device, and each of them get stuck in an endless splash screen (I waited more than 20 minutes.) I did not mess with the stock ROM slot, so that is still intact. This is really frustrating, has anyone else encountered this problem? I've already tried factory resets and data wipes on the ROM slot, and also have deleted and re-partitioned the slot twice. As suggested online, I was flashing three zip at once: the ROM, kernel, and superuser.

HAAAALP

[Q] Safestrap 3.75 Data Allocation Issues topic

I have come to discover that if I try to allocate over 4Gb of the Data partion safestrap only allocates 4GB. For example I wanted 7 GB and when I checked I only Got 4, I didn't even start to flash anything yet. What is causing this?

[Q] Proper Rooting and SafeStrap Process NC4 topic

Okay so I've been browsing through the forums and been reading up on this phone (even contacted Samsung about info on unlocking the bootloader, no go on that. Had to try though)
Basically I want to know what's the proper procedure for installing custom roms on an NC4 device.

Things I know:
Bootloader is unlockable at the moment (hoping for some good news in the future)
Towelroot for rooting
Safestrap for recovery
(Both just download and install the apk)

Things I don't know:
Kernel?
Somebody said I had to flash the NC2 kernel via Odin?
Knox?
What is this? What trips it?

I did see the list of guides and I did read and watch all the necessary ones, but the date on those are from 2 years ago and I just need confirmation on if I'm going about this right.
Any help is appreciated. I thank you in advance for taking the time to read this.
Please excuse my lack of knowledge, this is my first Samsung device.

Also, what would happen if somebody were to flash the DE stock files via Odin to a Retail N3?