Well bascially installing an amp and HU is the same as any other car. For the HU, you basically need to have the correct harness and kit, which you should know since you've done it to your 99' before.
Now I got a question for you: Are you planning to buy an amp kit? Usually the length of the power cable and pretty much all cables given in the kit is the correct length, which is about 17 ft.
Typically when "punching" a hole thru the firewall, it's done where the clutch would be. Meaning driver's side. Reason being is that driver's side has the power and the passenager's has the RCA cables. In that way, no distortion or any probs will happen. Also I find the driver's side to have more room to work with cuz the passenager's has the fuse box and other things that might get it in the way.
There's not much difference from different generations of Hondas. Once you have mastered one yr, you've mastered it all! haha