As I said the last time this came up, almost certainly yes. Disney has big expensive lawyers and they are both expensive and scary. Did I mention they're expensive? It doesn't matter whether you'd be legally in the right (you probably wouldn't), Disney could still drag you into court and eventually bankrupt you in legal fees and even if the court ruled in favor of you, congratulations! Now you're broke. Are your "fans" going to buy the video in enough volume to offset the court costs? Sources say no.
AFAIK that's not actually how parody laws work, so no. Don't do that.
It certainly does, but here's the thing; lawyers can't prosecute everyone who's in violation of their copyrights simply because they don't have the manpower to do so, so people say "well X got away with it so it must be ok".
I always ask people if they want to be the one random guy that the Mouse decides to make an example of to discourage others from trying the same thing. Do you?
The other thing about cosplay is that cosplayers are usually pretty careful to indicate that they're not representing the character/company in question and they're also not (usually) doing anything to hurt the brand while in costume. Porn most certainly doesn't fall under that umbrella. And again, even if they did, Disney isn't going to prosecute Joey Random for wearing a Sonichu costume to LocalCon. They're going after the big-name cosplayer that's attracting sponsorships based on same. This is definitely where a video producer stands more chance of running afoul of the Mouse and its lawyers, because you're monetizing a copyrighted image in a way that's harmful and misleading to the original brand.
Marvel (owned by Disney) has indeed shut down a number of fan films about the Punisher. It seems they take it on a case-by-case basis a lot of the time, though.
It also doesn't even require an image; I had a calendar revoked for sale on Zazzle because I made reference - in text - to the band Spinal Tap, and the company that owns the trademark on Spinal Tap contacted them and told them to take it down. Was I legally in the clear? Probably. Did Zazzle care, and made me remove the reference in order to get reinstated? Why, yes. Yes they did.