Regarding this:

iMinMemoryPageSize=100000
iMaxMemoryPageSize=5000000
iMaxAllocatedMemoryBytes=1800000000

Under papyrus of Skyrim.ini
It helps to fix lag etc.

Question:
1. Will it really fix missing meshes, ctd, random game freezes? The game works fine until 1.5.26, where i get a bit of crash everywhere(no its not mods). Did some tweaking(e.g. create new skyrim.ini etc, and it helped the CTDs but i still get some)
2. What do the numbers mean..?
3. I am currently using the 64hz fps limiter to remove stuttering issues. Do i have to remove that fpslimiter if i want to add these lines

Messing with those values is not recommended. It's generally best to leave those values at the default.

If changed, you can reset them by backing up your INI files and then deleting the original ones to let the game regenerate them and then apply any tweaks you want back to the refreshed ones.