Yes, it needs to be refrigerated after opening. It is mainly raw eggs and oil. It is shelf stable prior to opening.
The sauce should not be unrefrigerated for more than 2 hours. Less time is better.
No, mayonnaise is a condiment.
No, mayonnaise is not a gas. Mayonnaise is a semi-solid or thick liquid.
It depends on the mayonnaise. You can even get egg-free mayonnaise which is equivalent to an infinite amount of mayonnaise for each egg.
Usually they are about the same.
mayonnaise
Mayonnaise is a noun.
Possibly...
No. There are hair products that that use the word "mayonnaise" in them but it is not the mayonnaise you eat.
Mayonnaise and mayo are the same thing. "Mayo" is just a shortened version of "mayonnaise."
Mayonnaise Spoilage Myths - Mayonnaise Safety http://homecooking.about.com/od/howtocookwithcondiments/a/mayospoilage.htm
What is Aioli mayonnaise flavored with?Garlic!