Be carefull with the backroads... I've nearly killed myself twice, and have learned to keep the real driving to the autocross course.

Wheels wise, if you've got steel wheels you should probably chuck 'em. Crx, integra, delslo are all decent factory 14" alloys. I think the thinner 5-spoke found on delslos and integras was the lightest of those. For a factory 15", integra LS, gs-r, and civic SI wheels are good options. Of those, the LS (mesh style) is the lightest, then gs-r(blades), then gsr(5 spoke), then Si.

If you get 14s, I would definitely get falken azenis 195/60/14.

With 15s, kumhos are nice an cheap (what I'm running right now), and AVS ES100 are pretty good too. Azenis will still offer more grip than either of these.

Dont bother with 16s.

As far as suspension... The only thing that would really be damaged by lots of autocrossing is the bushings. If you replace them, I'd go with polyurethane, as its much better for performance, and usually cheaper than OEM.