First of all, symlinks don't work on Android's emulated storage (/sdcard). See this answer for details.
Secondly, when you format external SD card as Adoptable Storage, it's mounted at /mnt/expand/[UUID], which holds a file hierarchy very similar to /data partition, like /data/app, /data/data and /data/media etc. If you migrate your data to newly created ...
Question 1: Is there a drawback to making the /system partition as full as possible by selecting the biggest fitting GApps package?
Whether you install the smallest or largest version of GApps, /system partition will remain the same, unaffected in term of its size. The partition size is fixed for the device by the manufacturer (Yes, if you are rooted it is ...
whats the os version?
install gapps from this site: OpenGapps
mini installs to the system partition, if the rom version is higher than 8.0 (android version) is (the most times) the system partition smaller
try first gapps mini, if you get a error try pico
(sorry for my bad english)