If they had moved the USB and audio jack to the top there would have been room for a monster battery.
the back cover looks like is had space for a wireless charge pad but as the 6p is metal and could not have wireless charging they wimped out.
The likely problem with your wifi is not the card but the antenna leads that go into the plastic clutch
. Ifixit don't have a guide to change this as it it includes the isight camera so the screen has to be disassembled which is fairly hard
I got round it by using the camera cable from the old set and cutting off the new one
I wish they would find another way of securing the battery, this is ridiculous.
The fan is 18.2 dB(A) at full speed which is fairly quiet.
I just had to change my 2011 macbook pro 13 inch battery as it was getting pitiful, if there is no way of easily changing the battery it will probably be the last macbook I buy
As stated the keyboard connector is a nightmare to get back in, how I finally did it is, I presented the cable to the socket and using a sticky label pressing down pulled the label towards the centre of the mainboard
The magsafe connector is not under the mainboard and it would be easy for apple to have designed it so that the socket was on the top not the underside of the mainboard