Was Geordi supposed to have been able to see the entire spectrum simultaneously?
Yes, pretty much.
Would the human brain be able to process all those visions simultaneously and in a non-disorienting way?
With enough training, it could probably learn. After all, some people can see more colors than others can (due to varying degrees of colorblindness and such), so the amount of bandwidth the brain is capable of processing isn't fixed.
What if a person with normal vision put on Geordi's VISOR, would that person get the same super vision that Geordi gets?
No, of course not. It's just the external sensor for a system that's wired into his brain. Those blinky electrodes on his temples are the connectors for implants that transmit the VISOR's input to his brain's visual cortex, in order to bypass his nonfunctioning optic nerves.
Worf, himself, perpetuated the Klingon warrior stereotype. Worf was a member of Starfleet. He was under no pressure to be a warrior, not from his adopted parents or anyone else. He could have chosen any occupation, yet he chose the one job that was closes to being a warrior.
No, because Worf is not an actual person. He's an imaginary construct whose actions and decisions were dictated by the real-life writers who told stories about him. It was those writers who decided to make him perpetuate the Klingon warrior stereotype. They could have decided to give him a different personality instead.
Indeed, what you're saying is exactly why I think the writers' choice was flawed. It was established in season 1 that Worf was raised by humans from childhood. So having him be ultra-Klingon in personality and values was a questionable choice, basically defining him by his race rather than his individual life experience. Granted, they managed to rationalize it as Worf trying extra-hard to be Klingon because he was cut off from his heritage, but that's not the only way a character like that could've been written. Case in point: Michael Burnham. She's in basically the identical situation to Worf -- orphaned in childhood by an enemy attack and adopted by a family from a different species and culture. And she chose to embrace the culture of her adoptive parents rather than the one that corresponds to her species. There's no reason the writers couldn't have had Worf do the same, if they hadn't been so bent on portraying him as "the Klingon guy."
I don't know, maybe Worf had a biological imperative to be barbaric (from a human/Starfleet perspective) like a real Klingon.
That just makes the racial essentialism even worse. And it's belied by K'Ehleyr and B'Elanna.