Soft tissue grafting on gums. Will everything even out, and smooth out? How long does it take?

Two issues. The larger the graft the less it shrinks and the color of the tissue is determined by the donor site. Folks to tend to scar or get keloids, tend to wind up with lumpier grafts. If that disturbes a patient, it can be trimmed later. I would not do that for three to six months after the graft.
This will vary. The results will vary depending on where the grafting is being done, how much they are trying to cover up and your own bodies natural healing ability. Of course the experience of the surgeon will have a great influence on this. Ask to see some before and after photos, but bear in mind that the long-term results will depend a great deal on how you care for your teeth and gums.
Yes. As has been mentioned, there are variables, but generally the vast majority of soft tissue grafts heal completely by 6 months. If they are still "lumpy" after this, we can use an electroplasty machine or a laser with just a small amount of anesthetic to sculpt it smooth. Occasionally but not often, a surgical revision of the graft may be necessary.