double glazed door/window-best relative glass thickness?

[Pepeluis]

Hello all,
sorry been under the radar for a while. Found myself a bit caught off guard as a consequence of my own inadequate planning, have been having to make some crucial decisions very quicky and have been kicking myself for not having given adequate thought to some issues. I am sharing some of my oversights (despite feeling embarrased!) in order for others to not make the same mistakes and also to seek further advice if possible.

In the last few days the surface mounted electrical trunking has been fixed to the walls (please see pics). For the electrician to then proceed I had to give him precise locations of all the sockets I want and define whether they are to be for audio related devices, service (kettle , printer, fan etc) or heaters. decided on 12 audio sockets and 10 service, overkill?
Although I had a pretty clear idea of where each piece of gear would go (similar to my current setup) I was a bit caught out by exact location and number of sockets. this I think was partly because in the past I have never had a choice and always had to just work with what I had! I literally had to enact my recording procedure in my head to try and ensure I could comfortably reach the desk whether standing to record my vocals or seated to record guitar. This would be different if I were left handed but had to really think it through.
Another issue which I spent hours measuring and sketching to get a clear solution is where exactly to put ceiling lights. I am initially planning on having 2xGIK 244 absorbers as a ceiling cloud but until I have some gear set up in the room I can't accurately determine where the speakers would be and therefore where the reflection points on the ceiling will be and consequently where to put the lights to not interfere with the ceiling panel placement. I rang GIK (UK) and got some good advice to allow space to add ceiling panels if needed in the future. This then led me to think very carefully about where and what orientation I want the lights so as to leave space for possible future panels. I then made sure i have ordered lights with a 350 degree tilt/rotation so I can throw light onto my desk from their position which would not be right over my head. lights go up day after tomorrow.

One question maybe someone could offer advice on although I am sure it has been answered a thousand times before is how to deal with the cable penetration as it is right now.
Builder fed cable from outside via a trench , into cavity (filled with 100mm RW) between outer OSB and inner layers of PB, it then came out through PB wall on inside (ps cable visible in pics fixed to adjacent fence is unrelated leftover from a demolished shed).
The builder initially caulked inner penetration but later (to my dismay) the electrician pulled and pushed to loosen it and dislodged all the caulking! I had an in-depth conversation with him about the importance of sealing it again very thoroughly. He assured me he will do this but I am unsure how to direct him.
I asked if he could put the penetrating section through a piece of conduit then stuff with rockwool then caulk at surface, the caulking was no problem but he said he can't now put the cable through conduit. Not sure if this is right but have read similar guidance on this and other forums.

Short of ripping it all out and starting the penetration process afresh is there something I can advise him to ensure the best seal?

Where the cable emerges is approx where the service box will be, I had a thought that if the sealing is inadequate that I could have an isolating box built around the service box (think I read in Rod Gervais's book)

The other issue which has been doing my head in (as we say in uk!) is the realisation that the plan I had to use a Powerline network for internet access may or may not work due to the fact that the studio will have a separate service panel with it's own RCD.
Sorry if this is for a different forum topic but still may serve to help someone else plan better than I have!.
I know I could bring a phone line from the house 20m away then relocate the router to the studio or bring a Cat5 cable but I understand the cat 5 should not run close to power cabling due to interference. either of these 2nd options could require a 2nd penetration which to me sounds like a disaster!! electrician suggests if needed it could come in via hole drilled under the door!!

I may have to resort to my least prefered option which to most may sound the most obvious which is a wifi signal boosted from the house. reason I don't want it is the health risks for anyone within 15' of a wifi router i.e. my family members. some may think I am a crank but the info is out there and credible.

so to end my rambling post main questions relate to

sealing cable penetration

how to bring in a CAT5 or phone line if Powerline network doesnt work (won't know until electrics up and running)
Any guidance much appreciated
thank you
Jose