Yesterday, I rode 63 miles on a restored Fuji Supreme 12 speed bike. It has 2 chain rings up front and I feel that to use this as a touring bike, I would need to add a granny gear ring, so that would not have to walk the bike above a certain grade - which I did yesterday.

Question is
Do I need a new crank set with a third set of holes to add a third ring? What will be the most economical way to add lower gears and where do I get it?

Also, at high speeds, I feel a very regular bump in the rear wheel, as if the tire is going over a set of grooves or bumps on the road. At slow speeds it is smooth. Wonder if this is a wheel out of the true or a bearing problem in the rear hub. I have attached a pic of the crank before restoration.