Hello! Thanks, I'm glad you liked it.
1.) Showing bond system - So far, no plans right now. It needs more programming knowledge on my end to make a custom menu just for that. While I could learn the skills and make assets for it, I would rather spend time and resources on completing the game as it is now since it is functional. >.<
2.) Yes, there will be a sort of "romance" mechanic more similar to Fire Emblem Three Houses.
3.) Probably not. However, to compensate for it, there will be Grade Stamps available and higher exp yielding monsters in later dungeons. Furthermore, the max level cap is 50 and levels don't really give much stats. Most of the stats will come from equipment to encourage crafting. In this way, party members who are behind in levels can still be useful.
Come to think of it, there can be side-quests or side-activities to give certain characters extra EXP upon completion as a way to make them catch up.