Definitely not. The casting of Ryan Reynolds as Deadpool happened in the film versions. The comic had its own set of creative teams and no direct connection to his casting.
It's hard to say for sure. Sometimes the cast's schedule and availability determine if they'll attend Comic Con. Keep an eye on the entertainment news for updates.
I don't have that information. But you could follow the social media accounts of The Flash or Comic Con for any possible announcements regarding the cast's presence.
Yes, there are. Some movies draw inspiration from various sources but not directly from comic books. For example, 'The Truman Show' has elements of a fantastical world but isn't based on a comic.
Well, a blank comic book isn't really an actual comic book in the usual sense. It doesn't have pre-drawn characters, plot, or dialogue. It's more like a canvas waiting for your imagination to fill it up.