# Binding his donkey ... to the choice vine

Both statements mean the same thing. It is implied that the vines are so full of grapes that the master does not mind that his donkey eats some of them.

# his ... he

Possible meanings for all occurrences of "his" or "he" are 1) they refer to Judah's descendants or 2) they refer to the ruler in Genesis 49:10.

# he has washed

"they will wash" or "he will wash" 

# the blood of grapes

This speaks about the grape juice as if it were blood. This emphasizes how red the juice is.