Some folks demonstrate why the word "customer" starts with "cus!"

That said, DO NOT GIVE ANYTHING. You are being milked. When the job is done, this *** will think that is the time to re-open negotiations. Have your lien ready, and play hardball. Greet every request with "is it on the print?" If not, get a change order.
Some folks also like to ignore your advice, and mould their recollections to sit the moment. DOcument. And charge for everything, even a wasted trip.
The worst that can happen is they fire you....and that might be an improvement.