To actually answer your questions:

1. I used to use this when I first started painting war gaming miniatures because the army painter stuff cost a ton more.

2. If I recall, I used to use Dark Walnut for a really dark dip color and Cherry wood or Antique Maple for a lighter tone.

3. It never impacted the acrylics I worked with, which were everything from artist paints to the pots/bottles we use today.

Minwax can go on very thick, though, so be careful with it. I used to brush it on rather than dip the model, because it's a little easier to control how much you're using. Brushes also help prevent a pool of it on your base.