Speaking with a woman to whom one is not related (i.e., not mahram) should only be for a specific need, such as asking a question, buying or selling, asking about the head of the household, and so on. Such conversations should be brief, with nothing doubtful in either what is said or how it is said.
The idea of limiting speech with women to the five instances mentioned in the question – which are: to ask how her family is, for medical purposes, for financial purposes (e.g. in a shop), to find out about her personality for marriage suitability and to give her dawah (Islamic knowledge) – needs to be approached with caution, because they could be taken as examples instead of limits. One must also adhere to the conditions set out by the Sharee’ah even in instances where such conversations are necessary, such as in da’wah, giving fatwas, buying or selling, etc. And Allaah knows best.
In the answer to question no. 1121 it says:
Women are not prevented from talking to non-mahram men when it is necessary to do so, such as dealing directly with them when buying things or conducting any other financial transaction, because in such cases it is necessary for both parties to speak. A woman may also ask a scholar about some legal Islamic matter, or a man may ask a woman such questions, as is proven in various texts of the Qur’aan and Sunnah. Within the guidelines described above, there is nothing wrong with a woman speaking to a non-mahram man. It is also permissible for men to greet women with salaam and vice versa, according to the most correct opinion, but this greeting must be free of anything that may provoke desire in the person in whose heart is a disease, so as to be safe from fitnah and pay attention to the regulations outlined above.
If there is fear of fitnah being provoked by this greeting, then the woman should refrain from either initiating or returning the greeting, because warding off fitnah by neglecting the greeting is warding off mischief, and warding off mischief takes precedence over doing something useful. (See al-Mufassal fi Ahkaam al-Mar’ah by ‘Abd al-Kareem Zaydaan, vol. 3/276). And Allaah knows best.
Thus it is known that we do not mean general talk for no need, or a great deal of private talk. Rather it should be just as much as is needed in order to reply.
Going into detail in permissible talk or in shar’i matters when there is no need for that leads to removal of barriers between the two parties, which may lead to negative consequences.
And Allaah knows best.