Oh yes, they're very into environmental issues and being one with the land. On environmental stuff I find myself very aligned with their way of thinking. Yes, I wrote about them visiting various stone circles for ceremonies and rituals during the solstices on a few occasions.

There are modern druids but there were ancient druids as well. I believe the two were quite different.

According to Wikipedia, the earliest record of the druids comes from two Greek texts of c. 300 BC. So, yes that would be later than Stonehenge, but I'm not sure that means they weren't around before that - just that there weren't any earlier records.