I'm not sure what is still happening, but in regards to the database tables, it depends on what was installed previously. Most of the extensions are easily recognizable with jos_program-extension-name.
Have you enabled errors in Joomla Global Config (maybe even changing from default to maximum error reporting in the same Global Config).
Before messing with the tables, try disabling modules, plugins and CB plugins first. Usually that does the trick in narrowing down the culprit... unless you're like me and work backwords with a clean DB and J! install, then installing things one at a time to check thngs out that way. One day, my site will be up and running
If you aren't sure about the DB extensions, I'd look up the extension in Joomla forums or using a web search by searching for jos_whatever to see what you come up with. I'd begin removing the tables you are sure of that you suspect may be the culprit, one at a time.
Hope this helps. If you come up with some errors, it may help in getting an answer here faster than going the long way around with the disabling or deleting tables.
Jamie