Gonna replace brake fluid using the "Invalid mode" approach, have some battery/key fob questions

Hi guys,

I'll try to keep this short. I'm going to keep my 12v connected to another car while doing this job.

I was wondering what other sorts of precautions i need to take for this. I'm familiar with normal brake fluid jobs, but not with these electric pumps/hybrids so please humor me with any dumb questions:

1. Do I need to make sure the hybrid battery has a good charge before doing this job? I'll make sure its charged anyway, i'm just wondering if this could be a potential concern. Like if someone did this with 2 bars on a weak battery could they get themselves into trouble?
   
2. Do I need to worry about opening the driver side door and/or keeping the keyfob away from the vehicle, after it's in invalid mode? Or does it not matter, in this case.
3. In the videos I watched, they used bleeders that used a vacuum, do I need all that? Can I just use the standard clear tube into a water bottle and turkey baster for this job?

I will be doing it the same way nutsandbolts did it in his video, are there any important details he didn't mention? Any further precautions?