2, one before and one after the catalytic converter
Yes
Exhaust system.
You can not bypass it. The oxygen sensors are required for a proper running engine.
no
No.
Its located in the exhaust pipe on rear of engine.
21 is for the oxygen sensor reading staying at center.
No.
Next to the oil filter and oil pump. Wheres two sensors down there its the one on the left.
2, Before & after the catalytic converter.
There isn't a vacuum line going to the regulator on a 1998 Dodge Caravan.
No. A 1998 Dodge does not have a reset button or kill switch.