Actually, I am kinda worried about whether to write the story in prose or script format, even if I am initially going for a script. Purely because it can take a while for me to come up with prose stuff from time to time.

Use script for the first draft, maybe?

(My prose writing is sort of a mashup of the two when I'm first starting something. Paragraphs paragraphs [SUMMARY OF BIT I CAN'T FIGURE OUT HOW TO WRITE JUST YET] paragraphs that take place well after the bracketed bit...)

That does sound like a good idea.