Re: remove forum/”topic”/number
It works if you are willing to download the latest TRAC version from https://trac.bbpress.org/browser/trunk/ and then scrolling down to the bottom of the page and clicking the ‘download in other format – Zip format’. That is the latest development version. Then you have to change your config.php to have:
$bb->mod_rewrite = 'slugs';
Your .htaccess file should just be back to whatever you had before. Mine is just the + MultiViews part.
Trent