Why is it so important to use a face primer before applying the foundation?

Yes, you should. Don't forget the after treatment.

There are different kinds of conditioner oils. Read the instructions on the package. Most of them come ready to use unless otherwise stated.

All parts are important. Which is the 'most' important depends on the perspective you look at it from. The introduction is important in that it draws in the reader's attention...

You usually only need one or the other. Really it's whatever you like. I personally like primer better, but it is up to you. Try both and see which one...

No. You have to hold the extensions against your hair and then apply the heat. Heating the keratin on the hair creates a bond that attaches it. You then roll...

Yes, it is okay to apply both primer and milk of magnesia, but be sure to completely wash your face when taking off makeup, or else you will break out...

You don't have to, but it is much healthier for your face, as it can prevent acne and clogged pores.

As long as you have the right eye-shadow colors and eye-shadow applicators, you should be able to create a look that resembles the one in the tutorial.

You should do both. Washing your face first gets rid of the excess dirt and oil, making the mask more effective. Washing your face afterwards gets rid of any residue...

Yes, you can. But it probably won't get that much brighter. Try it out! I would recommend you mix two different colors for luster.