The audio doesn't bother me - in fact, I would suggest to you that if you do want to explore alternative audio options, don't discount the current setup. The sound is clear - and that is what is important.
Exposure issues are, indeed, a pain for cameras that 'automatically adjust'. They seek an 'average' which does not always work. To properly set the exposure - especially in a studio environment - you need to set up your lighting so it gives a fixed amount of illumination and then set the exposure settings based on this. Note: the subject matter - whether it be dark or light - is not relevant to this setting unless there is compelling reason (If you do have reason, then things can get challenging).
For general shooting, fixed lighting (sounds easy when you say it fast) and fixed exposure will be the best way to go. I think you will find that this is what Dave does.
The same goes for white balance. Automatic or preset white balance options are a bit of a crap shoot. The only way to get it right is with a camera that allows manual setting of white balance. You will also need a test panel to set the white balance. A piece of white paper is not too bad, but I use an 18% gray card from Kodak. Care must be taken, however, that whatever you use for setting white balance is, in fact, neutral - ie. it has no coloured 'tint' to it. Using grey items is not safe, unless you know they are neutral. A lot of grey coloured items have other tints that you will only notice when held against a truly neutral grey.
This video did not have any noticeably distracting colour balance issues - so what you are doing is OK for now.
+1 on getting a pointer.