Is a suitor considered to be overstepping by requesting to discuss pending matters face-to-face with the woman he intends to marry in the presence of a third party, and is he wrong if he requests to formalize their marriage contract with these matters to be addressed later?

There is no religious impediment to a man speaking with a non-mahram woman when there is a need, as long as it is within the bounds of Sharia regulations. This controlled communication does not constitute "taking secret companions," which is forbidden in Islam and refers to establishing illicit relationships. It is permissible to sit with her in the presence of someone who negates privacy, in order to discuss problems, and this is not considered exceeding the bounds of what is proper. Likewise, there is no harm in marrying her and then addressing issues, even if future disagreements are feared, as agreement and setting foundations before marriage are more preferable.