98 legacy GT needs LOTS of work

[luvmylegacy98]

so i have a 1998 legacy gt 2.5. my sister blew up the first engine so i put a stock replacement in it from a craigslist donor car. the front right caliper started sticking so i replaced it with the caliper off the same donor car. but it did it again and ground the pads down to nothing so now its metal on metal. am i going to need to replace the caliper and rotor with a brand new one? the car has also been hit before and rebuilt so nothing fits right. but the parts car hasnt. if i were to remove the entire front clip from my car and switch it with the donor car front clip how much work would it be? how long would it take? where could i find new headlights, mine are just about pointed at the ground from a hit-skip someone backed into at pretty quick. new front and rear bumper, between my sister and my father my car takes a beating. and a new hood, again from the hit skip. the engine also has a faint ticking noise at lower rpms. at first i thought it was a rod knock like the first motor but it goes away at about 2800 rpm. then i thought it was valve or lifter noise, i dont even know if the boxer uses overhead cams or lifter or what. but judging from the placement of the spark plugs i think it could be piston slap from a shorter skirt on it. i love this car to death and i want it to last as long as possible. i plan to begin working on it after i get through this winter and i heard it gonna be a bad one (my other car is a summer only car) so i have some time to start doing research. i really do want to save this car, i also want to put an sti 6 speed in it with a ej20 single turbo. but that will all come after everything is straight and nice.