How can one deal with a quick-tempered father who misunderstands speech, and is he entitled to ask his son to spend on the family from his own money while he has savings and land that he refuses to dispose of?

One must be gentle with the father and obey him in what is good, and assist him in matters that do not involve disobedience, and be patient with what emanates from him, in compliance with Allah's command and seeking reward. As for him taking his son's money without needing it, to spend it on his children as a way of saving his own money, he is not entitled to do so Islamically, because the maintenance of his children is obligatory upon him. However, if he is in need of assistance, then the son must help him.