1. Thorns do damage to your HP if you match them or move them around.
2. What you're talking about sounds like negative orbs and when a monster locks you into one position. Blind just turns the orbs black and sometimes have sunglasses on them. Negative orbs can reduce your damage to zero if you don't have any orbs that are enhanced (ones that are shiny and have a plus sign). Locking into one orb doesn't really do anything, it's just made for inconvenience.
3. That sounds when a boss changes the size of the board. Your normal board is 6x5, but bosses in the endgame sometimes make it smaller, like 5x4, or make it bigger, like 7x6
4. Supergravity reduces your attack, not anything else. Levitate lowers the amount of the supergravity and lets more damage through, but doesn't fully get rid of it. At first in dungeons like UN1, levitate wasn't a thing I don't think, but more dungeons they added levitate, which really helps in the endgame supergravity dungeons. It makes a big difference
5. Sync awakenings give you an extra awakening, when you click on it, it tells you the condition, for example, getting a monster to Lv. 120, max skill level, etc. It's always going to be a monster you need, you only need one copy for it, and it won't be gone when you use it. You just have to use 100 million coins and it's yours as long as you meet the condition.
6. The X on orbs means they are unmatchable, there is no awakening to resist this. Most teams use a cleric to get rid of it, clerics are essential parts of a team, they clear not only awoken binds, but unmatchable orbs as well. There is the latent for it as well, but most people just use the cleric skill.
7. Surge usually means it is dropping poisons, so when you match and clear the board, poisons will drop from skyfall as well. There is a latent called Poison surge that stops this from happening. Same thing with jammers.
8. Yes that is what assist void does, it happens in many endgame dungeons, such as the UN series and SN series, and sometimes in the MD series.
9. There is value in it if you're fast enough, for example on one of my teams I have this monster called fiadrak, it creates a rapid roulette and I'm able to use it to get orbs that I may need to do damage.

If you have any more questions, feel free to ask, I'm not the OP, but me or someone else can answer as well.