I'm a new multiboxer myself, so can really only answer one question.

Keyclone works, and works well. You can download a version - in fact if you look at the menu bar at the top there is a link to keyclone that downloads a file.

I downloaded keyclone the other day, and have been running so it seems that it may be runnable for a period of time before paying.

I wasn't too clear on how you pay for keyclone, whether it will pop up when a trial is expired.

For macros for various classes I tend to type wowwiki <class> macro into google - you could just go straight to wowwiki and type it in to their search box. There are loads of macros, they wont have multiboxer macros.