It feels a bit anachronistic to see the article writer referring to the nacelle caps as "Bussard collectors," a terminology that wasn't applied to Starfleet nacelles until TNG (courtesy of Rick Sternbach, who'd worked with Dr. Bussard before becoming a technical consultant on TNG).
It's also anachronistic to speak of the TOS Enterprise
having a "warp core," or to refer to TOS landing parties as "away teams." A lot of Trekkers do it, though.
I'm pretty sure you're right about the C or D cell batteries. I don't remember which though. It was nearly 50 years ago.
No, it was definitely two AA batteries. If you happen to have an unassembled kit and some C or D batteries lying around, try and see if they fit. (They don't.)