Education IRA: You are correct that you will not be able to accumulate much in the current formulation, even if you start at birth. I guess Congress did not have a calculator handy the day they set the groundrules. See other listings on this message board for some alternative ideas.
Using your own Roth IRA for your kids education: my view is this is not a good idea. Once you create a tax shelter (the Roth) you want to keep the most amount of $$ in it as long as possible. If your kids are young, the world (and your personal finances) will change signficantly before they start college. You may ultimately decide to borrow rather than disturb your Roth. One aspect of paying for college that most people overlook is that for 18 years you have been paying for food, clothes, housing, etc for a child out of your normal income. When you kid leaves for the big U, the real significant additional cost is tuition. I would suggest that you invest with the goal of paying tuition from the accumulated assets and plan to pay the room & board out of income. I think that is a more realistic goal for college savings.