A Yes/No answer doesn't cut it.
1. If your computer is infected, it could infect mass mailings from your computer.
2. It depends on the content of the popup script, a popup in itsself is not a virus, it is the malicious script content.
3. Similar answer to 1 above, if the autoresponder is on your computer or the host is compromised (reputable company should take precautions to combat the spread of viruses), it could spread a virus, but more likely not.
4. Much the same as 2 above.