Does prodelision in Latin just happen in verse, or can it appear in classical prose (e.g. Ciceronian), too?

Answer 1

Elision, including prodelision, does occur in Latin prose, particularly with forms of the verb esse. It's not a mandatory or universal rule, but more subject to the will and preferences of the speaker.

We know that this elision occurs both from modern textual analysis and because classical scholars like Cicero and Quintilian explicitly discuss it in their writing. For more information, see this article: https://www.jstor.org/stable/25010955?read-now=1&refreqid=excelsior%3Ad6897eaf1e12fd329851a0cc0ad2696c&seq=1#page_scan_tab_contents