Maybe I don’t understand your question… but
Hiding modules only with css (i.e hiding them on screen) does nothing for the power saving.
You need the monitor to go in to sleep for any power to be saved.
The Pi still runs when you hide the modules, not much power to save there, And I don’t really think the modules reload when hiding/showing them. But I can be wrong haven’t looked in to the code on the Hide/show part.
https://forum.magicmirror.builders/topic/6061/which-screen-for-magic-mirror/7
Get a VA panel monitor with high contrast, built in speakers will save you space if you need sound, it won’t sound any good (as if they do anyway) built in behind a mirror, but it will work. And a bonus you don’t need any external soundcard or filter to reduce noise on the pie’s 3.5mm outlet since you will take it via the hdmi port.
IPS panels are a waste behind a mirror, you don’t need that color accuracy which is the main benefit of IPS.
I would say the BenQ, since it is VA and has headphone outlet (3.5mm) so you could use that audio output to run speaker/speakers.
@dæmoneyes air circulation, screens gets hot, nothing to do about that, but either you have a mirror frame that has a larger air volume or you make holes, top and bottom, to let air circulate around everything.
The link sends you to a paypal site with dutch language,
Not a big deal, but should be English as default 
Edit : And also, Donated ofc!
basically it’s registers the location of an object (i.e your finger) when an infrared light beam is disrupted.
So the ir frame goes on the outside of the mirror.
Search for touch in the forum, it has been covered many times.
But the basic is that you need an ir-frame to get touch functionality.
I’m sorry, but are you expecting even more of Mitch than he already has given? Personally I think he is well worth a donation without asking anything more from him.
Domain name costs money, webhosting costs money. Especially if you have a lot of traffic and need reliable service (trust me, the cheap web hosts may offer " unlimited bandwith" but that is rarely the case in reality).
If he gets more funds over what the pure running costs is, then kudos to him. He can maybe take some time off work and adress fixes and improvements. (You get more done on a 10h day than a 2h day). But this is (for me at least) not a demand. As long as the donations first and foremost goes to keeping this forum and the repository online, any left overs Mitch can do whatever he wants with.
And, “one time” donations is the better choice in my opinion. Just don’t do the awful nagging that wikipedia did/does. (I donate, but I wan’t to do it on my terms).
And a title that says “sponsor” is the best option (with a 1 year time limit) as a “reward”.
For a well lit/daylight you want a light transmission of 30-40%.
A normal lit room with no direct light from windows I would say 20%