For example I was downloading the latest cgminer and Avast blocked the download saying it was a virus. Is this true or is it a false positive? I've had other antimalware (I think Malwarebytes) detect cgminer as a virus.
Antivirus and Windows defender will block most of the Miner programs and wallet files. They are false positive and you can add exception to it. Before you do it make sure you've downloaded the program from reliable resource. Here is a interesting guide which I found on this