Thanks, eschwartz - I'm currently using your second option but in a "dirty" way = I'm live syncing the actual library onto the RPI with the server running... That works "well" (until it doesn't...)
So, I want to have a workflow which is as "lazy" but safe. So, having a dedicated "books to import" (Sync) folder and - say - a (crontab) script which (shuts down the server) and imports the books from there every hour or so seems to be a good method.
Naturally, if one would just give the server an import folder and the server would check that folder every few minutes and auto-imports would be ideal but I guess that IS too much to ask
I could also run a script as you mentioned from my laptop for the import but in terms of workflow I'd prefer an "automatic" solution. I'm using a number of different computers, etc so keeping a script up to date w/ different IPs etc seem tedious
Thanks a bunch for your help!