Regarding your comment on wood fired plants: To me it seems that you imply that that is not renewable, which I do not understand. If you regrow the trees that you've burned (cleanly) down then your net impact will be zero, right?
Re 1: I would also rather have an easily replaceable battery, however for your use case I would think that a powerbank is more sensible than a second battery: no swapping/downtime and you can recharge both at the same time.