Here is a partial questions and answers with Christina Smith who designed MAC Lashes for MAC Cosmetics:

Why do you think lashes are an important part of a women’s regime?
Lashes create fullness, evoke sexiness, an can be used in many capacities.  They open the eyes, and frame the eyes, they can create an emotion or a mood depending on the style worn and most importantly they can positively effect someone’s confidence.

Why did you collaborate with MAC to develop a new Lash Collection?
First and foremost, lashes are fabulous! Everyone should have access to buy, wear and enjoy lashes.  You can change the entire look of someone by simply adding a great pair of lashes.  Part of the success of my business is largely due to the fact I make the only handmade, made-to-order lashes in the industry, which explains why a large portion of my clients are celebrities.  As you can imagine making custom lashes takes time and energy, which results in them being a little pricey.  It was important for me to work with a cosmetics brand that cares about their professional clientele as well as their customers, and by working with MAC, we were able to take all the design elements that I use in the creation of my custom lashes, and make the entire collection that is affordable, unique and wearable for everyone.

Please walk us through the steps of applying false lashes?
Step one: hold a mirror below your chin, look down into the mirror, so that your eyelids are fully extended.
Step two: apply a thin amount of Eyelash Adhesive evenly to the lash band. 
Step three: let the adhesive dry for about 30 seconds, until it becomes sticky, and not wet.
Step four: affix lashes on top of your own lash line.  Let dry for a few seconds. 
Note: I recommend curling and applying mascara to your own lashes before applying the false lashes.

via an official MAC press release.