Installation works when you follow instructions
So, after a lot of fighting and kicking and screaming, I finally successfully installed the latest Nightly. I was, prior to that, using Honeycomb. HOLY smokes, what a jump. I literally feel like I have a new tablet and am loving my GT-P7500, now.
I found that I kept getting an error message, during installation, and it turned out that using the correct recovery is important. It's not good enough that it's a Clockworks recovery, it has to be a specific on for the P4. P4 has it's own, P4-wifi has a different one etc. READ THE FIRST PAGE AND FOLLOW THE INSTRUCTIONS. Don't be a moron like me.
I also want to confirm, for those for find this reply via Google after searching for days (like I did), that this ROM works for the 3G+WiFi Galaxy 10.1 GT-P7500 and keeps both connection options. My only problem is that, for some reason, I can't download directly via 3G from the tablet. I don't know what the matter is - it's probably a bug that will have a fix.
Wi-FI downloading: Works
3G downloading: Doesn't work, the file is stuck on "downloading" for a long time and then the tablet decides "f*ck it!" and kills the download.
What's weird is that, if I tether my phone via Wi-Fi hotspot to the tablet, with my tablet running on 3G, I can download files just fine from the phone. It's clearly not a network problem, then.
Do any of the mods or CyanogenMod geniuses know what I did wrong (if anything)?