I just have somethings to say about the black Spider-man issue
Before you start hating me and calling me racist hear what I have to say first.
To start off, there's the fact that the sudden change from an image that has lasted since the 60s would not only be very jarring but also one has to take in the idea of transference of powers. Everybody knows Spider-man as a white guy, that's the way he's been written and drawn since the very beginning, so there would have to be some explanation as to why there is this very abrupt change in characters.
For example, superheros like the Green Lantern or Blue Beetle have seen a change in race, Green Lantern going from white to black and Blue Beetle from white to latino, because the powers were granted by some sort of item or gadetry and were thus able to transfer easily from one person to another. Spider-man's powers on the other hand came from a once in a life time bite from a genetically mutated spider. That spider never shows up again so one can only assume that it died soon after. If it didn't then there would be animals and other people who would have Peter Parker's powers which would utterly destroy the continuity of the original story.
And besides there are plenty of superheros who are "white" but are actually of a different species all together. Hawk Women, Martian Manhunter (okay so he's a little bit more green than white but his name, J'onn J'onzz, sounds French to me), Starfire, and Superman for example. Though of all of those examples only Superman got a movie, which is unfortunate. Because we could use more super-heroine movies that don't over sexualize women to the point of them just being objects to be stared at.
The point is if you really care or respect the comics as not only a source material but as a story that's been around probably longer than you have lived than you don't change things around like that with out some clever, plausible and interesting explanation.
Also, I am latino, and though I would like to see more latino superheros like Jaime Reyes as the Blue Beetle, I do not go around changing already drawn and published characters to fit my wants. That would be selfish and disrespectful to the original artists.
P.s. I don't think Glover would fit the role all that well. From what I've read in his bio here, he hasn't been in any other role other than comedy which doesn't fit in a superhero movie. Sure there are funny parts but he would also have to hit the dramatic cues at least decently and the intensity of the life or death action sequences as well which could be hard for a comedian.