next beta is not scheduled yet, meaning that there is not an official date for its release but the dev team is working on it.
the current beta is not supporting j1.6
the next beta proabily will, btw the stable vm1.5 will support it for sure.
about your testing environment, shop can be accessed by creating a menu link and choosing VirtueMart as the menu type
a clean database is mandatory as there is no conversino tool atm (even if db tables that needs to be converted are very very very VERY few!)
if you are a PHP developer, don't waste your time, give us an hand