Once a creature has been blocked, that creature remains blocked and will deal and be dealt combat damage even if it gains or loses shadow or if the blocking creature gains or loses shadow.

Multiple instances of shadow on the same creature are redundant.

If an attacking creature has multiple evasion abilities, such as shadow and flying, a creature can block it only if that creature satisfies all of the appropriate evasion abilities.

You draw a card and discard a card all while Looter il-Kor's ability is resolving. Nothing can happen in between, and no player can take actions.