What is the process of painting on Stucco walls?

Is a primer required?

What type of paint should I use?

Rolling or spraying?

What would be the min. temperature to apply the paint in?

A lot depends on the condition of the stucco, It needs to be clean of dirt and mildew and dry. I'd primer it with Kilz and then spray with my Wagner Paintcrew but a long nap roller may work if the stucco isn't too textured. Any name brand house paint like Benjamin Moore should be fine. You should expect to pay around $35 per gallon. Masterchem Industries, Inc.

If the stucco is not painted already, then the stucco needs to be etched with muratic acid or Drylok etch (comes in a powder). Long nap rollers will work fine.

Primer depends on the condition of the wall although be prepared for 2 coats.

Drylock cement paint works very nicely as a base coat. You could paint any color after it. It's specifically formulated for cement. It's quite thick.
Sometimes it' s best to apply to a damp wall.

Any good Latex paint would be fine.

Paint application temp can be found on the paint can. Generally the amount of humidity affects dry time.

The ETCH is EXTREMELY IMPORTANT. I can post pics of what happens when you don't etch.

Remember to repair any stucco beforehand.

I have not heard of using a acid wash on stucco before painting, but it is recommended that you let it cure 3 months if it is new, clean it with a mild soap and brush then paint it. See this link for a good product to use and application instructions.

Behr.com: Products - Masonry, Stucco & Brick Paint Flat