I love the flywheel it makes the engine rev so much quicker, and if you shift quickly the revs wont drop much.

I wouldn't go with anything less than 13-14 pounds, anything less than that and driveability will be comprimised, stop and go traffic will be a nightmare.

As for the install if you have the tools and the work wont be a big deal go for it and throw in a good clutch while you are it.