"They told you the calipers are sticking"? I would be careful there. The pistons are meant to retract only enough to keep pressure off the pads. Pull the pads and see if the pistons move back into the calipers with pressure. Be sure the master cylinder cap is off and have something to catch fluid overflow. If you can press the pistons back in and the rubber piston seals are not compromised, the calipers are probably fine. Make sure you turn the calipers and repack the bearings while you are it. As to the rears, as long as the shoes are fairly evenly worn and there are no gouges in the drums, leave them alone. If not, replace the shoes and turn the drums.

Strongly advise turning calipers / drums with brake replacements. You don't, you will damage the new pads/shoes. And you may not be able to stop fast and on a straight line.