[@Pleek]
Your 2-point Bond doesn't have to be related to your Arc! Your Affliction does, since the rank of your Affliction matches the rank of your Arc Trait (both start at 0).
[@Scarescrow]
>is XP used to level up our character like in the DnD?
Nope! XP is used to complete Quests, which are like little punchcard dealies that give you a specific reward (or "perk") upon completion. Completing Quests also puts XP towards your Arc, which is like a meta-Quest that shows your character's overall progression!
>can normal skill be upgraded as we complete a chapter or books?
Nope! Skill upgrades are a perk selection specific to your character's Arc, but the rules are so absurdly, needlessly complex that it's easier to just explain on a case-by-case basis after figuring out how someone wants their character to progress! Chapters and Books relate primarily to wound recovery, Issues, and MP expenditure.