The fish you suspect have TB need to be isolated and treated with anti-biotics (prefferably added to their food) or euthanised. You also can't use water changes alone to cure ich - you need an anti-protozoan med for that. I don't think you should add any more salt as it'll just be stressing out the scaless fish. I don't know about your angel but it sounds like she has an excessive amount of slime building up. Test your water and make sure there is nothing that could be irritating her and do lots of water changes. The build-up can be caused by parasites like Wilder mentioned or may be due to poor water quality or chemicals in the water. Water changes should solve the latter two possibilities and the ich treatment may be enough to kill off any parasites.