If the Department of Justice moves ahead with its adoption, the ADA will have a new look. However, like all parts of the built environment, if signs need to be replaced, then they should be replaced with signs that follow the new rules, not the old ones. If you did the research and found out how to make signs that could be easily read by touch, then you may already be following most of the new guidelines. The new standards call for tactile characters that are sans serif, with a fairly thin stroke, and that have discernable space between each character. Highly condensed typefaces are out, as are italics.
Braille has a rounded profile.
Visual characters now must follow a size chart that depends on viewing distance. Most other standards remain the same. Yes, the sign section is much longer than before, but that is mostly a matter of spelling everything out in detail, and separating the various components of a sign into different sections. The answer to the third question lies in the second. Because the new rules seldom conflict in any way with the current ones, you can begin to use almost all of them right now.