After FUT strip surgery, does the "donor dent" eventually even out with the rest of the scalp or will this already remain?

There is no "dent" after a FUT or strip surgery. It doesn't matter if you have a tight scalp or a loose scalp. If you are having issues, it is best to discuss with your doctor.

After FUT surgery, sometimes you can feel an area of scaring but overtime this should heal and the so called “donor dent” should not be prominent. 

The so called " donor dent" depends upon the healing in the donor area. If the strip is narrow, and the healing is good, there is hardly any change in the level of the skin above and below the suture line. And if the strip is wide and there is hypertrophic scarring or keloid formation, then it becomes very prominent. So, it will be best to meet a FUT surgeon in person and get a physical examination done to get a better idea.