I won't be like some of the others on here who will go on a rant about using the search function.
As for a simple HID explanation, This is a very informative article, If you don't understand something feel free to ask:
That particular projector that caught your eye happens to be known as the Gen III Projector, Generation 3, etc. The Gen III is currently the best in terms of output out of all the Jeep projectors compared to the Gen I and II's. You can either get them with LED angel eyes (The rings around the low and high beam) or with CCFL's (Cold Cathode Fluorescent Lamp) which some manufacturers claim are 4X brighter than LED angle eyes.
As for recommendation's for an HID kit, If you're pressed for cash at the moment and want to get the projectors but you are not sure if you have enough money I would go with DDM. I know people on here go head over heel to recommend XenonDepot (I've heard their products are great) But a kit from DDM (Link below) goes anywhere from $30-$40 and an extra $10 for each if you go with the 55w vs 35w for increased light output. I'm not in anyway affiliated with them but have been running a 55w 4500k kit from them for about 7 months with no problems. If you're looking for a cheap lighting solution they offer a lifetime warranty (But anyone will tell you that a lifetime warranty is only good as long as the company is in business lol) A kit from them along with a Gen III projector and you will be set. If you have any questions feel free to PM me.
As far as the HID kit goes, I'm not sure if most WJ users on here installed a relay harness with the 35w kits but you will definitely need one for a 55w if you go that route. A relay harness is a nice safeguard because it draws power from the battery so the electronics in the vehicle aren't prone to getting damaged due to the initial high draw of the HID kits. Lastly, If installing an HID kit in the low beams isn't enough and you want to do your fogs as well (if your model has them), Most people suggest going with a 35w due to the high heat build up some claim can happen from the 55w (which is running stock wattage lol), I'm not sure though.
Lastly, if you are concerned about upgrading to a higher output high-beam most would not recommend an HID kit. I don't understand the fools who try to justify installing one for several reasons. 1)
You lose the ability of flash to pass or being able to signal other drivers due to the hid's not being instant on like halogens. 2)
It's not good for HID capsules to turn off and on in a short amount of time. 3)
How often do you really drive with the high beams on anyways? If you live in any kind of urban area I doubt there rarely used. 4)
Since there is no projector with the high-beam there will be massive scatter loss 5)
An HID kit in the low beams and a Gen III projector you'll probably never need to use them.
A good alternative is one of these below: