I'm almost certain that what you're describing as "travel" is being incorrectly measured - if that measurement is being made with the wheels on the ground, what you're measuring is the available compression travel. It also looks like you have roughly an inch and a half of what looks like a compressible bump stop. If I'm right you'll need to jack the vehicle both wheels off the ground to see the total travel, which I would expect to be at the very least twice what you're measuring and probably closer to three times.
If you're unhappy with what you have (and that seems to be the case), I would suggest engaging the manufacturers/suppliers of the kit, but please be aware that their choice of components may have been deliberate - a compressible bump stop is often selected to "increase" spring rate as the suspension nears end of travel, allowing a softer spring to be used to permit a more comfortable ride.
Regarding the steering, under ideal conditions the drag link would/should be almost parallel to the ground (or the surface the vehicle is parked on) and also to the track bar or panhard rod if the vehicle uses one - this is not always possible and bump steer is the end result - I am not certain what you mean by lateral frame flex, and in fact shudder at the thought that the frame on any vehicle would/should be flexing laterally - it sounds like that would be the result of poor engineering design. Looking at the pictures, maybe I missed it, but I see no evidence of a "hi-steer" kit, and the steering could probably benefit from a drop pitman arm.
