Earlier today I would have said the new avatar image is nicer, but its not as detailed as the older one.

Maybe like you suggest - keep the old one, but with the new colours?

As for Krita. I think the best way to learn it is just to create a new file and play with as many brushes and filters as you can, then try to remember how you did it so you can do it again when you sell the first one for a handsome sum

There are also lots of variously useful/not very useful videos on Youtube for learning how to do different things.

Labels are really terrible in Krita. I don't think the developers realised they might be missing a really important tool and haven't bothered to develop the labels/text tools all that much.