im a cosmetologist so i would say if you want to use those products just blowdry them into your hair prior to flat ironing...a lttle goes a long way with heat...just try it and see how it goes...i do alot of my clients this way and it doesn't come out greasy nor damage the cuticle of the hair...hope i was of some help
Just get a good pair of straighteners, some hair serum and some deep conditioning shampoo and conditioner or you could even straighten your hair with a blow dryer and a round bristle brush x
Olive oil is a great thing to point in your hair there are hair products with olive oil in it called OLIVE.
I would not suggest doing so because it will leave your incredibly greasy. It really isn't worth it.
And if your using heat on your hair always use heat protective spray x