Where can I get info with a view to classify malware based on actions performed by the them. Eg. modifying registry files, copying themselves into other executable's etc.
A good site, formerly known as
cwsandbox.org is now called mwanalysis.org. Just submit a sample and it generates a behavioral report. HTH.
For file and registry accesses, run it in a VM with Process Monitor running or upload it to here.
enter the Malware name here Threat Expert and you will get a lot of useful info about that Malware