There's some adjustability since most cut the fork with about 1" of spacers, which can be transferred from below to above the stem. I suggest starting out with an overly long fork, and spacers above the stem until you dial in the height, then you can trim the fork leaving 5mm of space above the stem. I don't like to use more than 1" or so of spacers (though many people use far more than that) and recommend a higher angle stem if more height is needed. (angled stems can be flipped to offer a greater range of adjustment).

Here's a stem angle and height and bar position calculator which will help in choosing the right angle stem for your needs. Work form your existing position relative to the top of the headtube (corrected for any change in headtube length).

To answer your last question, there's no need to paint the steerer tube, since it's never exposed. There has to be a continuous stack of stem and spacers from the top cap to the headset, otherwise the system cannot work.