art advice needed.

Hey. Its been a while since I've been on here, and since I've drawn. I have a few questions that I've always wondered though, and would love some answers / opinions.
I'll get straight into it.

First off, how do people get the reflection in the eyes, and the very light strands of hair, and the shine on the lips and nose etc..? I'm sure some will say with a 'neaded eraser' but I've tried that and don't get anywhere near the result I'd like. Little example of the shine in the eye is here ; click here. Do people maybe use a white pencil like white charcoal pencil or a prismacolour pencil to get this effect? Or maybe tinted paper? Anyways, moving on..

What is a water-based varnish pencil exactly? What does it do? And where could I purchase one?

Also, the detail some people put into drawings is crazy. I'm wondering, what pencils do you use for hyper realistic portraits ? I'm guessing you use a mechanical pencil for very detailed work ? What other tools are needed for hyper realistic portraits? I've been working in charcoal recently and I'm not a huge fan. I want to work on more cleaner, crisp, detailed work but I'm not familiar with what pencils to purchase that will help me achieve this.

Your answers/suggestions/opinions would be highly appreciated.
Thanks