Charity Phase (and a little about Super Munchkin)

[Loath_Golcar]

Hi!
After a fight (won or lost), you directly enter the Charity Phase?

And, in the Charity Phase, can you play cards from your hand or field, sell items, equip and unequip, use class/race abilities, exchange items, change class/race (specifically, exchanging a class for the SAME class), before having to actually pass or discard items for Charity?

(As a side note: if I discard and change my only class, do I lose Super Munchkin in the process?)