Are EVH guitars made by Fender?

Think of it more as a collaboration. EVH US guitars are made in the same Corona, California premises as Fender, Jackson, Charvel etc but in their own dedicated space with their own staff. Their non-US instruments are built in Mexico, just like Fender.

Are Wolfgang humbuckers high output?

Yes, they are pretty hot. Considering the 'Frankenstrat' humbucker (based on a vintage Gibson ES-335 PAF pickup) had a low 7-8k DC resistance, this is about double as hot, measuring 14K at the bridge. It's a passive pickup and uses the Alnico II magnet.

What kind of radius does the fretboard of a Wolfgang have?

All EVH Wolfgang guitars have a compound radius of 12-16". This means the fingerboard starts off pretty flat and gets flatter still as it moves up the neck. This is a perfect situation for playing lead guitar on.

Does the Wolfgang have a flat top or an arched top?

Both actually, depending on the model! The Wolfgang Standard has a flat top whilst the Special and the USA models have arched tops.

How does the D-Tuna work?

It's actually a simple piece of machined steel that twists the exact amount to shift the fine tuner on the Low E to physically change tuning from E to D. There is no hidden device, it is as simple as that. Because of its shape, you cannot pull up on the tremolo bar since the D-Tuna would hit the guitar's body. Therefore, if you want to use the D-Tuna, set the guitar's bridge to be for 'dive-bomb only'!