1. Until W3C comes out with a final standard on aural stylesheets (which will probably happen real soon if I didn't miss it already) there will be things you can't do reliably. Once that standard is out, use it. The screenreaders will take a while to catch up, but your page will work (non-ideally) even for the ones that are behind the times.

2. Your main job when writing an accessible web page is to keep it clean. The more dirty tricks you play to get it to look right in browser A and B and to sound right in screenreader C, the more headaches you'll make for someone using browser E or screenreader F. Following the standards and the guidelines in the standards texts will take you far.