Yes, the batteries are includes, you can purchase spare batteries; and please see below for the spare batteries. I hope this helps.

Yes, you can purchase spare batteries; please see below for the product. I hope this helps.

Not at all. Weight wise I would say it pushes about the same as a gas mower, but this one has front wheel drive! No pushing at all!

Nope, they only sell the unit.

you would have to check and see if it is available at your local home depot. I paid around $500 3yrs ago for mine but it was worth every penny. I saw them recently and they seem to have come down in price for $250 range.

Itt is traditional lead-acid, I believe to keep costs down.
It has two 12 Volt batteries wired in series to provide 24 volts to the motor.
The charging setup is 24 volts also to charge the batteries in series.
You could probably charge each batteriy by itself with a 12 Volt charger, but each battery might not have the same charge which might result in ineffiencies when wired in serires.