Usually using just an AV from one software maker with just a FW from another works without issues. So in your case it should work fine.
Yes, it should work fine. You may want to add ZA main firewall executable "vsmon.exe" to VIPRE exceptions.
I have and use Vipre.Like ZA its a dual firewall(incoming and outgoing)are both top ranked,Zone Alarm and Sunbelt(Vipre) had great write ups in pc world and pc mag.Vipre by the way is the only vendor I have heard of that offer LIfetime pc licenses.selling or giving up the download and key for it on 5pc's good until Dec 17 this year now having lifetime... $29 renewal and a lot more time to check it out than the trial.ZA was my other pick option until the reviews backed up lifetime.no worries here about protection now.