apt question

I have a mostly working Linux setup that I have maintained and upgraded over the years using sources I've compiled and installed. I want to use apt so that I can test and checkout various applications and can remove them easily if I no longer need, or don't like them. How can I tell apt/dselect n

dpkg test option?

Is there a option that can be passed to dpkg that will just test the .deb package for errors and then exit? -- Fred

installing stable X?

I tried installing the latest X11, version 4.0.2 and found that some apps don't run, notably Netscape 6. How do I revert back to the last version of X using apt? -- Fred