two questions:
how does retiring work? what's the calculation for how many levels you lose / how many skill points you pick up?
Half your level, rounded down. You get +3 Skill Points and +3 All Stats, I believe, for a Level 30 Retire with an extra +1 to each for every 10 Levels (e.g., Level 40 Retire would be +4/+4).
Also, Retiring
deletes the character you Retire. You basically delete the old character and create a new one with bonus stats and it starts at half the level of the character you Retired (up to Level 30; a Level 99 Retire, for instance, gives you a Level 30 character still, not a 49).
also, I don't understand binds at all. a) do they count as status effects for N's damage boost. b) do they always work the same, i.e. does binding legs only prevent running? does head binding prevent magic? I have no clue what does what and if its consistent across enemies.
There are three limbs: Head, Arm, and Leg. Almost every skill in the game is associated with one of these parts. If that part is bound, those skills cannot be used.
On top of that, each Bind has it's own effect:
Head - Lowers Accuracy.
Arm - Lowers Damage.
Leg - Disables Evasion.
And, no, Binds do not count as a Status Effect for a Nightseeker's bonus damage.