I don’t really agree with the notion that 24p makes it look more professional. Certainly 24p has a look, mostly for stories that want to have that “suspension of disbelief. In this case, it is speeches and such, so not warranted from a creative storytelling technique.
More importantly, shoot progressive, regardless of frame rate, you will get full horizontal resolution compared to interlace. So 30p (29.97p) is fine, and usually a nice comprimise. 24p (23.976) has some tangible benefits in file size and data rate as it will be a 20% smaller file overall given the same parameters and that may gave value. Or increase date rate by 20 for more quality, etc. It will also give you 20% more shooting time on that card. 🙂
I do agree with the exposure discussion. At the very least get a gray card and do a white balance and exposure on that before shooting. This will give you a great start and better looking image.
Lens is a factor – but may have diminishing returns based on the codec compression of the camera.
Michael