I played Yuela's Route on first game. I'm currently on Serawi's Route on my second game. Just before the final boss battle. Some spoilers ahead.

Already Answered:

Unanswered:
5. How do I unlock the Ultimate Weapons of the Eushully characters? I believe they're called Infini.
6. Is there a way for the game not to pause, whenever I move my mouse on the very top of the screen?
7. Do the EU cards respawn? I need to craft more of their weapon and I ran out of recipes.

1. Each main heroine has a line of special weapons, ending with the ultimate weapon. Each of them requires leveling up the previous one; penultimate also requires 200 Knowledge and Sense. Serawi and Emelita's first weapons can be acquired only on their routes.

2. 10 is the limit. No idea about mods.

3. No. This world is unfair.

4. I suppose you could put empty/transparent images in place of those, but I'm too lazy to figure out what filenames you need.

Alright, new questions.