Changing terrain in ways/roads - How do you handle this?

General talk
1

Hi,
as I understand, a way or road consists of nodes that do not have any specific tags.
So what if the way is interrupted by stairs or if the road changes from concrete to cobblestones?
How does one tag this?

2

Then you have a street consists of 2 (or more) ways. Both ways have the same attributs and values except for the pavement.

[EDIT]: Here’s an example for a Road containing a footway, steps, bridge and beeing a residential street:
http://www.openstreetmap.org/?lat=50.204329&lon=8.571916&zoom=18