I haven't had Holeshot brand struts, but did have someone else's. Still, the answers to your last two questions will still be the same, regardless of who makes them.
Since these struts are part of the suspension system, anytime you alter their mechanical length, you change the amount of leverage applied. Since it takes a longer strut to lower the bike, it will apply more leverage on the shock, making for a softer ride. Conversely, a shorter strut to raise the tail (which is the way I went) will make it stiffer. Of course, all this assumes you have made no change to the shock, only the struts.
As for difficulty, I'd give it
on the
Shade Tree Howler Monkey Banana Scale.