Can I log in to V5 & 6 with the same account?
I want to keep and continue to use 5 (at least for a while), can I install 5 & 6 on the same machine and still use both?
Yes, if you are on Windows 10 double check that the option to uninstall the previous version is unticked.
I'm a bit worried that V6 might wreck my V5 library which is extensive to say the least
Your RB5 and RB6 database are treated as two seperate ones. So any changes you make in RB6 won't be reflected in RB5