I'm honestly going to try to help here. Let me clear something up first. There is no 1.3.1 version of the game. The .10 in 1.3.
10.0 is a ten, not a one. It is a newer build than the previous version, 1.3.7.0. Version 1.2 broke a lot of stuff, so I'm not going to help anyone roll back to 1.2 or 1.1. I don't know of any way to do it and it doesn't help the person having issues if they just run into the same problems the next time an update is released.
As I said before, the game ran flawlessly before I had to reformat.
Why, with a new patch, am I forced to run a 64bit program, as I'm lead to believe that the .exe is now, when I only have a 32bit operating system?
This is not correct, nor is it even possible. Making an .exe large address-aware is not the same as compiling it for 64-bit. 64-bit operating systems can access more than 2GB of system memory by default. The LAA flag for 32-bit executables is necessary to allow them to see more than 2GB, which as you pointed out, this means 3GB on a 32-bit operating system. The TESV.exe is not a 64-bit executable and compiling it as a 64-bit executable for users of 64-bit operating systems would not magically solve the problems people are having. In any event, you can not run a 64-bit executable on a 32-bit operating system, so nobody is making you do such a thing.
Still no response from the devs regarding this issue?
This is a self-help technical support forum. Bethesda monitors the forum but they don't normally post here. Gstaff occasionally provides updates and very (very) rarely posts in threads, but you should not rely upon or expect help from Bethesda by posting in this forum.
I'm not sure if it's just me, but since the "LAA" patch, I've been getting abnormal CTDs, and purple textures showing up.
I've run every version of the game that's been released and I've seen
some of the issues you've mentioned, but not to the degree you're now experiencing them. Version 1.1 and 1.2 were relatively stable - I encountered 1 crash (note: all crashes should be considered 'abnormal') but I saw slightly increased frequency with 1.3.7.0. This problem went away with the third-party LAA fix applied to 1.3.10.0 and didn't get worse with 1.3.10.0. Prior to 1.3.10.0 I've seen pink/purple textures after longer sessions of play (2+ hours). Restarting the game fixes the problem. I've seen it maybe 2-3 times, but I have plenty of system RAM and a fast hard drive.
Now to the actual problem. You have pointed out that the game was running fine before you had to reformat and reinstall. You've already tried different video and sound drivers, so that's not the problem. I don't believe 1.3.10.0 is the problem since I've never had these issues to the severity that you're reporting and many of the issues that you've pointed out were reported well before 1.3.7.0 or 1.3.10.0 were released. I think you need to take a look at your chipset drivers to make sure that all system drivers are up to date. This can include on-board audio drivers, disk controller drivers and usb controller drivers. You need to look at your Windows updates to make sure you have the latest (or at least the same as before the reformat) versions of DirectX, .NET Framework and any recommended updates. You should look at your swapfile settings. You can try configuring Windows to not use a pagefile to reduce hard drive thrashing. Look at whatever might have changed when you reinstalled Windows. I'm not going to mention mods or INI tweaks because those should be obvious first steps.
I don't believe the 1.3.10.0 patch is the cause of these issues.