As far as how far out and in and/or how tight, when the mechanism starts that "click, click, click" you release the button.
Since the drive mechanism is on the bottom of the slide the bottom of the slide will start the outward and inward motion first followed by the top of the slide. During the first operation of the season (putting the slide out) I've seen some fairly significant delay in the top of the slide starting to move but in six years of operating the slide it is still functioning properly.
There may be a slight downward angle to the slide when out and the TT is perfectly level but if it is it is a very shallow. I try to level my TT side to side as much as possible but it is rarely perfect and regardless of which side is slightly higher or lower we've never hand any water intrusion around the slide seals (we don't have a slide topper).