1. Soft lighting would be the best for a painting, try to keep them from direct sunlight.
2. To clean the surface, all you need to do is grab a soft cotton cloth, dampen it with water and gently wipe the dust off in circular motions. If the dust is excessive, you may want to use a feather duster first. You can also use a small piece of bread and gently rub it on the painting to take off dirt and dust.
3. Never use ammonia, alcohol, turpentine, bleach or any solvents to clean an acrylic painting.