I've looked around the forums and handbook a bit, but some things are still unclear.

1) Once you upgrade to CVS, will it be straightforward to change to the next major release once it comes out (4.6 in the current case)?
2) How does a move from 4.5.2 to CVS affect modules installed previously and content? Will there be a need to clean up MySQL database/tables after the upgrade? Or to somehow remove modules that are no longer needed?
3) I'd like slightly more detailed upgrade instructions than those that are in the upgrade part of the CVS install textfile. Specifically, I'd like to know which parts of drupal and its SQL database should be backed up first before upgrades? Exactly what needs to be overwritten - the contents of the previous Drupal folder with the contents of the CVS archive (meaning everything)?

I am still quite new to Drupal and would appreciate some advice on this. Thanks.