Oxygen sensor
yes
One is in the exhaust manifold on the passenger side, the other is in the exhaust after the dowpipe.
A MAF sensor for a Subaru Impreza can cost anywhere from $70 - $150 depending on the type of Impreza you have.
Screwed into the exhaust pipe.
no the primary one is the one closest to the engine
It's threaded into the front of your exhaust manifold.
The speed sensor on a 98 Impreza is on the gear box. it is on the driver's side under the bulkhead.
It's a code for the oxygen sensor.
Back side of the engine....mounted in the exhaust manifold.
I have had the same problem with my '93 Impreza. The button on the automatic shifter will not depress to take it out of park. There is an override option in the owner's manual but I think the real problem is the brake light sensor. Ocassionaly, when I can actually get it out of park, you can hear a clicking noise when the brake petal is pressed, this is the shifter-lock releasing. It must be the sensor for the brake petal going bad.
No , it is not an interference engine