Joker2040

Here's a re-creation of what they are using plus some of the mods suggested in the comments: http://www.technicpack.net/modpack/details/yogcraft-147-yogscast-pack.156638

Don't smelt ore blocks; make an Applied Energistics Grind Stone and Wooden Crank. Just 3 quartz dust, 3 stone/smelted-cobble, 2 cobble, and 4+5 sticks for double ores. Don't abuse the crank with the grind stone empty; I've had it break, losing a few sticks.

F11 just stretches the window to fill the screen. You have to select Full Screen Mode within Hexxit/Minecraft. Options/Video Settings.../Fullscreen: OFF.

Sounds like it could be qCraft.

Try full screen. I've heard it works. How to Fix Your Technic Launcher (crash bug + upsidedown screen bug) on Mac OSX

You set it to Adventure Mode, rather than Survival or Creative?

Make all mobs infernal and make the tougher versions rarer.

From Hexxit wikia: What causes chunk errors? Rapid approach to a portal?

<user>/AppData/Roaming/.technic/hexxit/Chocolate I'd move the Chocolate folder and see if it gets replaced. Or its contents.

<FTB launcher folder>/<FTB modpack folder>/minecraft/config/TinkersWorkshop.txt

I think there are bushes that grow Essence, similar to the berry bushes or the ore berry bushes.

Blocks from Secret Rooms cause this. This is terrible. You think to build a secret room for your best stuff, and it gets destroyed, because you hid it in a secret room.

Image search for Not Enough Items, find the Options screen. Hide/Show: O Press the O key.

Yep, it's bugged. I throw them into cacti to keep them from accidentally being used. It's safer than lava.

"Yes." If you want a challenge you can try making Rift Remover(s) and see if you can kill them faster than they spread. Minor Operator mode: In config/DimDoors.cfg change B:"Enable Rift Spread"=true to =false, and maybe B:"Enable Endermen Spawning from Rifts"=true to =false, at least during the removal. Then use the Rift Remover(s). (I don't know if Rift Removers are reusable or not.) config/DimDoors.cfg is located in your server folder or in Windows <user>/AppData/Roaming/.technic/hexxit/.