Altough you are right about this and I do also still have a zigbee network for these purposes, I did observe range, repeater, and stability issues. For light bulbs, which are not battery powered, there are more options to consider :)

I just want to kindly share experience: You might want to consider not making the bulbs smart but rather the wall switches. So you can still use the switch and also Automate it. If you should consider this, there are sonoff zigbee switches, but my experience with zigbee is not the best to be honest. I would rather recomment shelly wifi switches (IMO scaling and maintaining a smarthome wifi is much less pain and more reliable than zigbee.

This might not answer all of your questions and I only have very small number of cameras, but I would recommend to buy any IP Camera that supports RTSP and then create a seperate VLAN or LAN for the cameras to not be able to phone home or anywhere else. I actually have a complete isolated smarthome network using a opnsense Router and it works Quite well and at least feels safe.

Another way could be to invest in unifi / ubiquiti cameras, they have a good Reputation. Integration in frigate or homeassistant I dont know.

Its always DNS

The shelly Sensors are really nice.

Finamp, very polished, actively developed and cross Platform. Requires a jellyfin instance. But thats a nice diy project in it self, can only recommend

IMHO there is no perfect solution for this, but I switched to Searxng (which can be selfhosted) and Im happy with the results. Please note that Searxng is a Meta Search engine, that basically means its using multiple other search engines with less tracking afaik…

Are the external USB drives using a external power cable or just USB power? To me it sounds like you are hitting the Pis USB Power limit. You may want to get a cheap external USB dock with dedicated power supply

I tried both (for selfhosting and features) and Immich is way better IMHO

https://selfh.st/apps/