I love the brick as it is. Stucco will need permanent ongoing maintenance and, if you get much rain, can become streaked and discoloured with splashes and plant growth. Honestly, I would leave it alone. But get the crack fixed.

Ditto, too much maintenance. Leave it alone.

Our next door neighbors stuccoed over their slump block wall when they were selling four years ago and its held up beautifully. I think they went straight on the block with the brown coat but if it were up to me I would put wire on to be safe.

What about that crack at the corner? Seems like the wall needs to be repaired before covering it with stucco.