Hetty.........
Kiyeus, that's an impressive plant!
The roots/caudex look fine. All the tiny bumps are new rootlets, go ahead and water them along with all the roots as well as the potting mix. Looks like maybe a snail or mouse had a go at the plant, and ate some of the bark. it's all healed now, and making rootlets. You don't need to do anything with them.
I think the yellow bits on the leaves are some sort of bug. Scrape off the white things and see if they're squishy, like bugs. I haven't seen this problem before. Maybe scale.
Hope this helps, and Welcome here!
Oh, and come see us at:
http://garden.org/forums/view/... a whole lot of folks with Adeniums!