http://www.slhondaparts.com/
www.hparts.com

are sites I go to for dealer parts.

The gasket should be an easy fix, spark plugs shouldn't really cause a major lose in vacumm? But the healthier the engine the more vacumm it makes.

driveaccord.com admins sometimes have TSB's posted, but the dealer should be able to let you see any TSB's they have.