I currently have lots of legacy Flash files built in ActionScript 1.0 and edit them with Flash CS5.5
If I upgrade to Flash CS6 can I still edit these files and have them work correctly? (Flash CC won't let me, but will CS 6?)
Or is there an easy way to have AS1.0 flash files updated to AS3.0 with the same functionality?
Flash CS6 does support Actionscript 1. You should download the trial version to make sure of this and that it will work on your system.
To my knowledge there is no easy way to update AS1 to AS3 other than manually changing it from one to the other... some coding functionality does not exist in both so different approaches have to be implemented at times
You can download the trial version of the software thru the page linked below and then use your current serial number to activate it.
Be sure to follow the steps outlined in the Note: Very Important Instructions section on the download pages at this site and have cookies enabled in your browser or else the download will not work properly.