What exact chip is used for WiFi on the Librem 15?
Is this an integrated WiFi/Bluetooth chip?
Is the shut-off switch for both at the same time, or can you shut them off individually?
If someone at check-out does not choose to get a WiFi card, does this mean the person is not choosing Bluetooth as well?
What is the “socket”/slot for this chip, as in what is the form factor. Maybe I will want to buy a WiFi only chip and install it myself.
Thank you.
To elaborate on that a bit …
Because the switch is basically cutting power to the card, there really isn’t a way of simultaneously getting the certainty of a Hardware Kill Switch and the flexibility of separate control over WiFi as distinct from Bluetooth. You cut power - you lose both.
The only way of doing it would be to have two slots, two Hardware Kill Switches, two cards (i.e. one extra of each) and to source a supported dedicated WiFi card and a supported dedicated BT card - but that is not what is available.
So if you want separate control then you have to enable/disable in software.
That is absolutely the intention of the design.
You are free to order without a card, or to order with a card and then physically remove it - for certainty that goes beyond even a Hardware Kill Switch. 
You are free to order without a card, to source your own card and to install it. Of course then you take responsibility for getting it working, and you will need to be careful to understand what blobs, if any, are needed in order to get the card working - and to decide whether that is important to you.
Looks like M.2 but bear in mind that M.2 can be keyed in various ways.
M.2 itself potentially offers both PCIe and USB electrical interfaces (and indeed other interfaces, like SATA, all depending on the keying), and it is not uncommon for combined WiFi/BT M.2 cards to do the WiFi over PCIe (for the higher speeds) and BT over USB.
M.2 form factor is a separate question. It would be difficult to answer that without seeing the insides. You may need to ask Purism at support@puri.sm but I would guess 2230.
Of course, if you order without the WiFi/BT card, you also have the option of using an external USB WiFi dongle, which has advantages and disadvantages.
It depends on what your goal is.
If the goal is to avoid Bluetooth then many people would be happy to disable in software. Maybe you can completely remove the Bluetooth support in software, on the Linux side (and not just disable).
As the previous reply says, Bluetooth doesn’t work out-of-the-box anyway (for other reasons) so it depends on your level of paranoia.
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Thank you. I’m still confused. What I want to know is: what is the form factor I need to buy a Wifi-only chip for, to be compatible with these laptops? I understand I would be responsible for drivers.
Perhaps two reasons:
I gave you a guess but if you want to buy a card in advance of getting the laptop and opening it up yourself then you would need to use the email address I gave you.
Okay so you don’t know the answers to my questions. That’s okay, but I posted so I could hear from someone who does know. Someone who works for Purism for example. Thank you but I’ll keep waiting.
Quote from the link: This is BTW also the reason why we are still pretty stuck with the ATH9k in the laptops.
Just between you and me, I think this kind of detail (card physical interface format and, where applicable, form factor) should be on the Tech Specs pages for the respective products, since you can buy with no card. @joao.azevedo ?
Yes I agree. Any modular part should have the interface and form factor on tech specs page. But I didn’t find it there so I have had to post here. Is @joao.azevedo with the engineering team?