Hello everyone,
I was wondering if it would be advisable - because I know it can be achieved without much trouble - do host the wallet files on an external disc drive.
Will it stress particularly the disc drive in question?
Will there be any latency due to this?
Thank you for considering my questions!

There will be a delay, but everything will depend on the speed of your disk. Also, for ease of use, you can write a script so that the blockchain with all the files is in one place, it is very convenient if you store everything on an external drive or flash drive.
Example script(only Windows):
@echo off
cd /d %~dp0
start %CD%/bitcoin-qt.exe -datadir=%CD%
exit
Instead you bitcoin-qt.exe need to specify the main file of your wallet and save it with extension .bat
Then put the file that you created in the same directory with the wallet and run only from it.