Black Hair/Blue Highlights

Just a bit of a warning here; I know from experience that semi permanent dyes in darker shades do not wash out in a month, or a year for that matter. So, if you are considering using it because it might be easier to get out, in case you don't like the color, don't bother. I would reccomend asking your stylist what they reccomend and go with that. Either way, if you decide to go lighter again, it will take some chemical process to do it.

I have very fine, medium brown hair and have wanted to get blue highlights for a long time. Not the punky bright blue highlights, but the very subtle ones where you can barely tell they are there except when in the sunlight. I'm going to dye my hair dark for this, since this seems to look best on people with black hair. I need some advice on this, since this will be my first time ever getting my hair dyed, and I'm not sure about what color or type of dye to use.

First off, is black best? I have fair skin, so I'm a little worried about black washing me out, but I don't know if dark brown would look good with blue highlights. Plus I'm a little curious what I'd look like with black hair.

Second, what type of dye should I use? I'm going to go to a salon since I'm pretty sure I'd screw it up, and I like to play things safe. Should I ask for permanent or semi-permanent dye? What's the difference? I assumed the difference was that semi-permanent dyes wear off after a month or so and you get your natural hair color back, whereas permanent dye never wears off and must simply be grown out. However, my coworker told me semi-permanent dyes must be grown out too. What will damage my hair the least?

Thanks in advance for your replies.