Can you take a picture of the wheels it came with? The pictures I see of stock wheels look like alloys to me.
I'm not certain if they would fit, but some Honda stock rims are pretty good. I believe the 2nd generation Civic Hybrid wheels are about 16lbs each (and stock tires are 22lbs) which isn't bad for a 15" rim. For comparison, the 14" rims on my Insight are 11lbs with 11.5lb tires, and the well-loved 13" Civic VX rims come in at around 9.5lbs. The advantage of the Civic Hybrid wheels would be that they're already relatively aerodynamic:
If you can't find any info on them online, I'd recommend pulling one of your wheels off and standing on a bathroom scale with it. You can find the tire weight online and do some subtraction to get the rim weight.
Regarding side skirts, MetroMPG made a set a while back which is held in place with velcro:
http://ecomodder.com/forum/showthrea...metro-103.html
You might also try taking a piece of 1/4" aluminum, bending it into a U shape, and attacking it to the plastic liner inside the wheel well, then using that as your anchor for the skirt.