Yes, as they if run would execute immediately in the same way as an ordinary .exe file. The other archives in the list generally they have to first be unpacked and any executable run, before that happens it should be scanned.

The avast default settings are there to provide the best balance for protection and performance. Only when you know what effect changing those settings might bring, they should be left as is.

Re the “Files and programs have become “.ink” format” I think this is a windows setting and I’m not familiar with it. But a google search on what I have in quotes returns many hits, http://www.google.co.uk/search?q=Files+and+programs+have+become+“.ink”+format.

It depends on what your OS is, this one is about changing that in XP, http://www.computing.net/answers/windows-95/all-programs-changed-to-ink/166047.html and this one for windows 7, http://www.makeuseof.com/answers/change-fix-file-associations-windows-7/, I think this one also covers Vista.