Well that's what Steve Wang answered at the panel, and as I mentioned before, I haven't watched DK in a long time (Since episode 5) so disregard any inaccuracy in my report.
The only interesting questions in the Q&A section were the lack of Mark Musahi and next adaptation, the rest were very forgettable or were stuff we already knew (For instance, the last question was "What happened to henshin?" and Wang replied that obviously it doesn't work since not everyone is a harcore fan Kamen Rider fan nor fluent in japanese, he was trying to make a series that was respectful to the hardcore fans and at the same time, easily accessible to "newcomers"
I just remembered something, supposedly, Stephen Lunsford bought some Kamen Rider DVDs (He didn't specify which series or movies...most likely V3 or The First) from Amazon before they started filming, since he wanted to be familiar with the franchise.
The rest of the actors Matt Mullins, Aria Alistar, William O'Leary and Scott Bailey were oblivious to the franchise. Steve Wang was against showing Ryuki to the cast because he didn't want to influence their acting with the original series... or something like that.