Q1. I don’t know - is this what you mean?
Q2. Here’s a link to the platform specifications for the laptop.
According to it, the WLAN + BT module is an Intel Dual Band Wireless - AC 8265,
It has a M.2 2230 or a M.2 1216 board form factor
M.2 2230 - Package Size 22mm x 30mm x 2.4mm, System Interface Type PCIe, USB
M.2 is the new name for NGFF.
Q3. I don’t know - use the video and the manual to open the laptop and measure the space available for a card. From the video it doesn’t look like more than the size of the card that is already in there, which to me looks roughly like 22mm x 30mm (see dimensions above)
Q4. According to this video and the T480 service manual-p.73 the Wireless-LAN module has 2 antennae.
Hopefully this is of some help.