The enemy is leveling up when we leveling up too, right?

1. So, how is that calculated?

Are the enemy's level calculated from our average level?
Or it is more complicated than that?

Are the GF leveling up has something to do with enemy's leveling up too? Or only my entire party?

I'm just wondering about it.

2. What about Omega's Level? Is he the same calculated like any other enemy? Or no matter what level we are, he is just at the highest level (i_i) ?

3. Do you think it is always a good idea to fight the strongest O weapon at level 100 with 100 GF level too?

4. I cannot find the Jack from CC Sidequest, how to find him?
Oh, Please, I'm almost fall asleep when I have to find him!
Because he didn't show up, and I have to walk around challenging as many card players as I can.

5. Do you know how to get Holy War and Holy War Trial without doing this sidequest??

Thanks for the answer!!