I'm trying to troubleshoot my westinghouse sk26h730s which has 2 hdmi inputs and have trouble getting my xbox 360 audio to work via an HDMI cable. Do all HDMI versions support audio?

Yes, You probably have something set wrong in the Xbox or the set. There is usually something in the menu that allows audio to pass using HDMI. There could also be an audio setting on your Westinghouse set.

Yes. HDMI cable is HDMI cable, at least as far as supported 'features.' It's just the cable that connects the devices, the devices control all the data that is being sent over the cabling, and what features and modes are supported by the devices in question, and your settings, etc.