For those of you with more experience than I (ie. everyone ), I have two newbie questions.

1. Is there any difference in a $15 bike helmet from Target and a $50 helmet from a LBS?

2. With road tires, (my bike has Bontrager) will riding 50 feet over gravel/grass damage them? I have to cut through to avoid a narrow busy street and get to the park/bike route.

Thanks!