On your Mac Book Pro, for the overheating issue, have you tried using a can of compressed air to blow out the fan and vent areas to make sure it's able to move air through it? If it's fairly new, that shouldn't be an issue, but it's a common issue for laptops that are 2+ years old.
When you run icamsource on your Windows machine, did you first exit icamsource on the Mac? Also, it's possible the firewall settings are different on the Mac vs. Windows computers. Have you tried temporarily disabling any firewall software on the PC? Do you have "auto config router" checked on either/both systems in icamsource? If so, do you have uPNP enabled on the router?
Also, just to be clear, you can successfully add the IP camera as a source in the Windows system...it's just not passing it through to your phone/iCam, right?