'05 Civic Coupe.....hmm let me think about that for a while.
This is the mids and high section so we won't go to far off track into the SQ side. As for what ohms to get, purchase what ever will get your amp down to a 2ohm per channel to maximize output. Now, the down side to this although you maximize output you sacrifice some THD while doing this. Again though we are talking about only a fraction and with the amount of speakers you'll want the most output as possible.
Honestly I'd recommend picking up an external crossover or purchasing a head unit with one built into for accurate frequencies going to each channel on the amp. It may be confusing at first but, the more control you have the better in the long run. I hope this makes sense thus far.