Foil installation best practices + heater install order

Hi everyone. I'm about to install the foil. A few questions wrt that:

1. I know that a single layer of vapor barrier is preferred, but what about overhangs? Is a few inches of overhang ok, if I tape the seams?
2. What method of installation is preferred? Should I just use tape to mount the foil, or should I staple it and then tape over the staples?
3. I have installed blocking for benches. See pictures.  Should I install furring strips equivalent over the blocking? Otherwise there will be a gap between the blocking and the cladding and I’m not sure if that is optimal to attach the mounts for the benches in. However, If I install horizontal furring strips, I will certainly block the airflow.  Should I simply put a piece of furring strip over the blocking with like 1” gaps? (And just make sure I don’t drill screws into the gaps)
4. Lastly, how did you handle electrical penetrations for the heater? I have a Harvia Virta 11kw. As it is a floor mounted heater, I have the option to install it before I install the cladding. Would you recommend to install it first, test run the system and then install the cladding? I’m worried about things like the temp probe - any issues with that one and I am screwed basically.