The autofocus on the N900 is done through contrast measurement, which works quite badly especially in low-light environments.

At the moment the software which actions the camera hard codes the fact that in order to get focus, a minimum amount of light is required, at which point the flash will be triggered in order to focus correctly. This could probably be filed as a bug, bug plainly put, there is a good chance that you'll have a hard time to focus on whatever you're trying to shoot -- for the mass market it makes sense to use the flash for focus.

I don't think the red light is powerful enough to help during focus, and what was said before is correct, there is no need to have the red light going after recording starts as the focus is non-changeable during filming.

I believe the source code for the camera application is not open source, so this change will have to go through a software update, however, for the red light (used to indicate we are filming), this might be controlled by the chip directly in hardware. Someone could file a bug to request more information regarding this.

Hope this helps,