When I step on the brakes, the car seem to want to go to the right a little. Does this indicate tire / brakes problem or something else. I also feel like the truck is is a littel unstable at high speeds on the highway (moving from side to side). Are all these related.

Also. when I open/close the front sunroof, it makes a noise, almost like something needs to be greased. Any suggestions

 

Pulling could be from a frozen caliper or improper brake fluid pressure reaching one side. It could also be loose steering components. Get under your truck and start grabing rods for excessive play. Have a buddy move the steering wheel while your under neath to see if you got excesssive play. As for your sunroof grab some lithium grease and shoot the rails.

 

Check the radius arm bushings at the frame rubber mount. if there is any gap between the rubber its junk and will cause the car to wander.
lots of things in the suspension to check. if its only while braking this isint it , check calipers etc.

 

On both your questions you asked, you then asked, could it be, well what have you checked so far? It is hard for us to check your air pressue and grease you sun roofs.
We have a much better chance of helping you if you first check as many things as possible first.