Keith Hi Keith, thanks for your interest.
1,2&3 - you don't need any hardware, WW communicates directly with the Giv cloud API, and your inverter will need to be online (on Wifi) yes.
4 - we overwrite only the first charge or discharge slot. Main thing to keep an eye out for is accidental overlapping slots that will result in failures.
5 - Yeah, you can use our Pause Schedules function, which will pause all and any automations you have setup with us.