The memory thing is a part of the in game modding system, as the images are loaded into the memory. With them being pngs it can end up taking a lot of memory. Not much you can do about it right now since that was what Cyrk tried out first when figuring out the modding system. A future update though switches the mod loading system to something else, and while there is still some increase in memory being used, it is always less than what Discord uses and allows for many mods to be loaded at once while using the same amount of memory. So you'll have to wait for the next update (or join the Patreon) for that issue.
As for the ARK issue, I would need a few more details to try some things out. My guess is it isn't VT+ causing it since the mod doesn't touch the sprite loading system at all, so it could be a typo in the dialogue/sprites or maybe some in-game bug from something like spamming the space bar. Any details you can provide me like the amount of prey digested before it happens (is it consistent?) or maybe a specific prey?
Okay, so apparently the level up screen never triggers, but ARK does level up properly along with gaining the proper stats (and fat :P). Though its not all roses and rainbows, since the game still bugs out at times and doesn't clear the sprites from the screen.
TL;DR
Something in ARK's files causes the game to skip the level up screen and bug out.