This...won't do anything in an average household. A consumer grade router is quite efficient, unless you just turn off the entire device
A per-port choice of 1 Gbits/sec or 100 Mbits/sec. Apparently capping it to 100 Mbits/sec saves energy because they’re calling it a green setting. I’m a bit surprised the savings would be notable enough to justify the option.
It doesn't, unless you've repurposed a computer as a router, then the CPU has to do the heavy lifting of packet handling. The faster you go, the more it has to work, but any consumer grade router uses ASIC chips dedicated for Ethernet handling.
It's true cellular uses considerably more power because of the distance so you should use the far more efficient and local WiFi
Disable image loading in the browser. Most images are junk anyway.
Great for speeding up browsing on a limited connection, pointless for energy savings
Btw your reverse tethering option probably stopped being maintained because that is now built in to Android