A lil more input on the Accord as I owned one, gas mileage is not all that super, sure it's good but I was seeing around 24 mpg, mainly highways. Driving like a granny I'd see 26mpg and driving like an ***, about 20 mpg and getting 300 miles for the tank. IIRC, it's got a 17 gallon tank and you can get 400 miles out of it, I've done it several times.
I'd replace the lights. I had them on and didn't realize how rice they were till afterwards. If you want OEM's, I still have mine. I'd replace the spark plug wires as well, those orange ones are quite ugly.
Installation audiowise is simple, especially the head unit. Speakers, you'll a little more than 2.54" for mounting depth with 1/2" baffles, and you can't do 3/4" because it will make the door panel stick out, unless you want to cut the door like I did...was just a tad.
Also, I'd lose the intake...sounds nice, especially when the "VTAKKK" kicks in, but you're losing power. I know a guy who worked at a shop and dyno'd all sorts of intakes for these Accords and they all showed a loss. The airbox on them has a bunch of rivets which have some sort of purpose but I can't remember exactly what the guy had told me. I didn't really notice much of a loss, nor did I notice a gain with my CAI.
I must say though, when I got my Megan Racing coilovers, the ride was a beauty and it handled MUCH better.