About Wizard, what Gosei said.
Gentaro, he aspires to be something from the 70's and it's his personal flair. (And he's probably seen Grease too many times.)
As for Eiji.....I just can't think of a good quip or response other than he's a hobo.

Would someone care to explain how Inazuman knew Fourze in SHTZ?

"He came from the future!"

Okay then, how?

Also, in the Knuckle Gaiden where did the Marron Energy Lockseed come from? Come to think of it, where did they get the new Kurumi Lockseed and Sengoku Driver? The best we got was that Mitchy pulled them out of his ass.
I mean I guess I can buy that he took them from the Yggdrasil remnants that were stirring up trouble in the Gaiden, but if that's the case then why only give a Driver to Zack? Couldn't we benefit from having Oren and Jonuichi helping out with the Neo Baron stuff too?
They're probably saving it for the potential 3rd Gaiden I guess.

Micchy made the comment of Rogue Yggdrasil agents and scientists still making things. If anything I'm sure he and Takatora got it from one of those sources during a raid of sorts.

Inazuman knows Fourze because he's Gentarou's student from 20 years in the future, as shown in the Fourze/Wizard Movie Wars.

As for all the Gaim stuff, that got said in a novel, which you'd have to check FruitRiderNews for more info about, but it generally lines up with what you've already guessed. And, just to mention, Oren and Jonouchi do apparently get their drivers back :D

This happens when?! In the novel?

Apparently so!
http://fruitridernews.tumblr.com/pos...ynopsis-of-the
http://fruitridernews.tumblr.com/pos...en-rider-tokyo

And it finally gives us Zangetsu Jinba Melon.

Made no mention of Oren and Junouchi. Also, Jinba Dragon Fruit for Micchy?! OMFG. Never mind, reread it.

Says it right there on the same page as the Jinba Dragon Fruits thing.

I corrected myself.

I would have liked to see a filler ep in Ryuki that tells us more about Okubo the chief editor and his past relations to Shinji.