No problem with the rear brake lines as they are not affected by a suspension lift, but the front brake lines may (or may not) need to be extended if your front axle is capable of drooping enough at full flex to stretch the brake line. I'm not too sure but I'm not so sure an RC lift flexes well enough for that to be an issue.
On the trackbar, any suspension lift will pull the front axle towards the driver's side and the rear axle towards the passenger side. With a 4" suspension lift, they will be pulled enough to the side to be noticeable. Adjustable length trackbars are the best fit for this as they will recenter the axles back underneath the Jeep. You could also get a trackbar relocation bracket for the rear which is cheaper and will kinda/sorta recenter the rear axle but not likely perfectly. The front axle is harder and the only good way to recenter the axle is via an adjustable length trackbar.
The trackbar connects from one side of the axle to the frame on the opposite side of the Jeep. That's why it pulls the axle out to the side when a suspension lift is installed. Think of a trackbar as the angled part of the letter Z. As the upper part of that Z gets lifted (from the suspension lift), the trackbar (that angled center part of the Z) will pull the lower part (the axle) to the side. The axle would get shifted towards the right in the case of the Z example.