brake pads first, before rotors. unless there's warping, uneven wear. you would know this if when you brake your car leans to one side (left or right) even if you have perfect alignment. warping is unusual. for uneven wear and scratches, you just need to have it refaced.
-replacement of disc brakes(front)
palit disc brakes? are you serious with this?
although shops rarely have this, the best way to check on it is with a brake tester. try dropping by at our shop.

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for the shocks, KYB is the standard. you can have it refilled (cruven or zee's specialty). don't by from casa, they'd give you the assembly, coil spring and all.
tie rod, rack end and ball joints in front should be done, lest you want your steering to go awry. usually mechanics inspect bushing by pulling and pushing to see if there's play.
for the undercoating, have it done at least once every two years. especially if your area gets flooded.
have all of them done except for the disc rotor replacement. that needs second opinion. come to think of it, go for a second opinion for all of your concerns.
remember, a good suspension system gives you more control of your car.
do you know that a bad suspension system decreases your car's braking power by at least two meters? those two meters could mean life or death.