> However I have heard it is a pain in the ass to repair, and replacement
> parts are scarce.

Have not had the need to repair, but I was astonished it shipped with
brackets and FPC cables for the second drive.

Here is a link to the service manual

https://dlcdnets.asus.com/pub/ASUS/nb/Customer_self_repair_guide/X712EA_Customer_Self_Repair_Guide_20210701.pdf?model=k712ea

> How long is the battery life (typically with normal load)?

When I am on batteries, I am using the system to diagnose embedded
systems.  This includes the use of USB to serial converters and serial
terminal emulators.  I do embedded systems development with jtag
programming tools for uploading code to microcontrollers.  I also use
network tools such as wireshark.  This includes the continuous use of
WiFi, and the display of multiple video streams generated by our
systems.   In this sort of operation, I get about six hours if I start
at 100% and take the batteries all the way down.  I try not to do that.
I prefer to set charge limits to 80% and cycle to not deeper than 20%.

Eric