I have solid experience configuring and maintaining Linux, but my knowledge in networking is quite basic. What should my first configurations and preparations should I do before flashing Openwrt and setting it up for my home network?
PS. If I can use the switch as a NAS, I’d be delighted.

I am using booklore for the same reason as you and it works very well. The only feature I’m missing is highlighting, but I can live without it.