[Christ]

1) Yes. CRX's are more fun to drive.
2) CRX's are non-OBD, unless you update the car. Getting an HF doesn't give you an update option without losing the HF engine, so the only real choice is to go to a D15Z1 engine and full ECU swap.
3) No, except maybe the Si models, which would be able to be retrofitted to your HF
4)HF doesn't, Si's do. Some DX's I think. If you don't want it, the Civic and Civic DX racks will fit easily, they only take an hour to change.
5)Not even close, but the B6 is the 8-valve EGR'd version of the D-series engine, which will get you ~50 MPG w/o trying, if you keep it running correctly.
6)Depends on what parts, but not particularly. Some people want to charge a mint for them, though.
7)No, Hondas are actually very reliable. I hardly ever had to replace too many parts, excepting maintenance items, like ball joints and tie rods.