Good day;
Correct, transmitter of choice could be the wireless switch on the wall, or key-fob remote or combination of both. The relays can store up to 30 links so the switching configurations are endless.
Correct, we only manufacture 2, 4 and slowly phasing the 6 button switch out but yes. You could have one button linked to the plug module but to make life easier the second button can also be linked to the same plug module or to another receiver.
Correct, it is a 30A relay, down rated to 16A due to plug connections, so it is a larger relay than our "standard" s5 relay.
Regarding Alexa, yes you would require our GSM Cloud Hub, I am not familiar with your question regarding 802.11 but my programmers have advised that it does not make use of that and our GSM would be required.
Kind regards;