Will my hair dye fade?

I think how much dye fades depends more on the porosity of your hair and what developer the stylist used than on what type of shampoo you are using. If your stylist used a permanent tint and your hair was otherwise healthy, I doubt you are going to get more than a level or two fade at the absolute most.

It is hard to go back to blond (or to some extent even light brown) from dark brown (especially if you have multiple layers of tint) without using a color remover or bleach. I, personally, have not liked the color removers I have used. I have also found that the tints that supposedly lift tint have not worked terribly well (on my hair at least).

Again though, it just all depends on your hair and how many levels you need to lift, the general rule of thumb is that "tint doesn't lift tint". If it were me and my hair was healthy enough to do it, presuming I needed a lift of more than 3 or so levels, I would probably just bleach and tone and be done with it.

I suggest that you should use hair conditioner for colored hair. There are some available products of it that you can buy at the malls or drug stores.