Is it permissible for those with excuses who are allowed to break their fast in Ramadan to have intercourse with their wives or to smoke during the daytime in Ramadan, or must they refrain, and what is the evidence?

It is permissible for a person who is not fasting in Ramadan due to a legitimate Shar'i excuse to have intercourse with his wife during the daytime, provided that she also is not fasting due to a legitimate Shar'i excuse (such as illness or travel) and is free from impediments to intercourse like menstruation and postnatal bleeding (nifas). As for smoking, it is forbidden in itself at all times, and consuming it in Ramadan is even more forbidden and graver.