According to the factory service manual;
If the car has a 2.5L 4 cylinder engine the ac compressor relay is mounted to the firewall on the passenger side next to the blower motor housing.
If the car has the 2.8L V6 the ac compressor relay is on the radiator mount on the passenger side. There are also 2 other relays there.
The fuel pump on your 1988 Chevy Celebrity is in the fuel tank.
The 1988 Chevrolet Celebrity uses distributor-less ignitions. Timing is controlled by the ECM, there is no provision for adjustments.
No there are shock absorbers on the rear.
The oil pressure sending switch on a 1988 Chevrolet Celebrity with 2.8L V6 is located on the bottom of the block near the oil filter.
There is a fuse for the blower motor on the fuse panel, I do not know of a relay.
Metal.
The coolant fan relay on a 1988 Chevy Celebrity with 2.8L V6 is on the radiator support bracket behind the right hand headlights.
R12 unless it's been converted.
Underneath your hood, behind the passenger side headlight, behind the core support, is a bank of 2-8 relays. One of those relays is the relay needed for your fuel pump. There will also be a fuel pump relay fuse located there.
If your 1988 Chevrolet Celebrity has the V6 engine the oxygen sensor is in the middle of the exhaust manifold nearest the firewall. If you have the 4 cylinder engine the oxygen sensor is located in the exhaust manifold just above the exhaust pipe flange.
It on the back of the coil packs going into the side of the block.
The firing order for all of the Chevy Celebrity 4 cylinder engines is: 1 3 4 2