Questions about items and wandering monster

[Hazelanne]

Hi all,

Im new to the game i have a few question regarding items:
1 can u switch equipment during charity phase which said that u must play necessary cards, does it mean u can equip unequip during charity?

2 or can u switch items anytime except in combat, even in ur opponents turn?

3 does it applies aswell for selling items? That u can sell them at any players turn and any phases except combat?

4 if i play wandering monster lv12 to add a level 4 mob. Then somehow i discarded the lv12 monster. Does the level 4 mob still have +12 combat stats?