He sure can! Unlike most scientist, Eggman knows about magic and has combind it with science a couple of times (read: everytime the chaos emeralds were involved) so definitely!

Muraki would be welcome in these shenanigans.

As for taking a backseat, sure! Keep in mind, while some people would probably stay loyal to Eggman, most would probably ditch after his plan failed. So Muraki working with him but behind the scenes is a bit exciting and actually very clever.

As for the volunteer, I'm sure we could work something out.