provide info for both switches the same time. Do it by 'show spanning-tree interface', so it will be more compact.

Yes, it will work, as Hello packets will not be transferred between ports, if any link is down.

Panda is right. It is probably because of Encryption for L2TP. Check, that server and client sides use the same configuration. For windows you can check Properties of your L2TP connection and...

Btw, I checked it with win10 and it doesn't allow you to configure such MAC-address manually for your NIC, so I think it's normal behaviour from tplink side.

My bad. You do not have it in controller, while if you have AC50, then you have some CAPs, right? :) Exactly CAP (unbound from AC?) has WDS Settings.

No, ip-camera will not see internet, if you don't use default route on camera's router/switch. If you use it, then it will go via this route. In reality, if you want to keep camera local, you will...