Mineral oil doesn't really mositurize our hair it basically just sits on the outer shaft of the hair and coats it. This makes it very hard for the hair and the pores on the scalp able to breathe and secrete its natural oils. If you put hair grease/mineral oil on your skin it adds a lot of greasy shine but doesn't solve skin dryness.Now imagine leaving that on your skin for a week without washing your body...you're bound to attract dust, dirt, and feel as if your pores have been clogged to death. The same goes for when it's put on the hair. I have to say that the day I stopped using mineral oil and replaced it with moisturizing leave in conditioners was the day my hair got significanlty healthier and began growing significantly.
As far as parabens go...there have been some controversial studies as to whether parabens lead to cancer. Some say yes and some say no. I know wikipedia isn't that great of a source but they do have some references at the bottom that show the scientific studies.
Parabens: Due to recent publications citing potential correlations with some health problems associated with use of products containing these additives, many consumers find it less worrisome to simply use products that do not include these ingredients.
The above definition was taken from the CM ingredients section. Mineral oil isn't not absorbed into the hair shaft. It just lays on top of the hair preventing moisture from getting in. Mineral oil is also considered to be a cheap filler in some products. You may see it in the ingredients listed as:
Mineral Seal Oil
FYI: Most of the answers to your questions can be found on curlmart.com and by doing a search on the boards. Just click the search arrow at the top of the page and type in what you're looking for. There are hundreds of threads about ingredients. Hope that helps!