You are asking engineering questions for which I cannot answer without knowing how large the structure is, and not being able to do any load tracing. I can't test your soil, and you can't draw me a diagram of your building layout. (words don't really do it here either).
You need to hire a structural engineer to tell you what you need to do. He should have experience with OLD buildings, and should have certification in soils engineering as well.
most footing settling problems in older structures come from water penetration at the foundation, unless you live in texas, where the problem comes from a lack of water.
This is not the kind of thing you should do without knowing what you're doing. Painting your bricks is a stupid mistake, but it doesn't constitute a safety issue, nor does it have the potential to destroy everything you own or hold dear. Foundations are entirely different. EVERYTHING sits on the foundation. Do it right.