Yes, although in most cases the answer to "can I climb up this" is "yes." There are a few exceptions, but I can't recall exactly where at the moment. I believe the distance is about 6-7 meters though.
Yes, but not on a single wall. If you jump to another wall and hit it higher than your current elevation, you'll ride the new wall at the higher elevation. If you find a corner where you can bounce between two walls, for example, you can reach the top of the objects in question.And is it ever possible to gain elevation using Lucio's wall ride?