1. The 4g Civic Ex sedans are pretty rare and they have the same powerplant and output of the Civic/Crx Si. It has the 108 hp d16a6.
2. I don't know about the gauges but my guess would be they will be good for awhile.
3. The bodykits made for the 4g 4drs are pretty hideous. I know kaminari and wings west made similar kits for the 4dr but they are pretty ugly and outdated.
4. Intake resistor mod????
5. I have seen some 4drs with oem looking spoilers but I don't know exactly which cars they came off of.