Neither Euron nor Tarly are small roles (the casting call listings emphasized that both were really good, meaty parts). Those roles also wouldn't justify the secrecy. It looks like a small role but that still has an impact; that makes it seem like almost a cameo sort of thing. It being a ToJ Kingsguard would explain why they're tight-lipped around the role's identity. He's the right age and look for Hightower, too.
I guess I'm in the camp that thinks (wants?) the letter really was either the offer to put Rhaenys out of her misery or the threat to kill Aenys. Or at least, something along those lines. Even if it didn't provoke a Harrenhal-esque retaliation from Aegon, something in it freaked him. It seems like the support against this stems from the logic that "if that had been in the letter, Aegon would have destroyed them. Aegon didn't destroy them, ergo it wasn't in the letter." And I'm not sure that's the best logic to use. Isn't the whole point of Dorne's successful resistance that the dragons and army weren't sufficient to overcome them? If Aegon was so fully capable of taking out the Dornish if he wanted to ... well why the hell didn't he when he was trying to conquer it? And before the letter came, if Aegon would have instantly gone to rescue Rhaenys, why didn't he, if he thought she was alive? And if Aegon would have avenged her if she was dead, why didn't he, if he thought she was dead? He didn't have to wait for the letter to rescue her or avenge her, if that's what he was always going to do.
I think the Dornish had him by the inbred nuts and maybe some people don't like to admit that.
I think that depends on Wex's actual involvement in the Manderly plot. The cover story for the whole thing doesn't make much sense. How does a mute kid who's ironborn get an audience with Wyman Manderly? The truth will affect Wex's plot going on.
I do think they were married although obviously GRRM isn't going to beat people upside the head with it until it's ready to be confirmed. What is it with people needing every damn thing spoonfed to them in order to believe it? Especially in a series like this where so much of what's going on is implied or hinted at but never explicitly spat out.
As to who would have married them. They apparently eloped near Harrenhal. What's near Harrenhal? The Isle of Faces. What's on the Isle of Faces? A fuck ton of weirwood trees. What can traditionally be performed in front of a weirwood tree? A marriage. When Brienne and Pod are in the Riverlands, who do they encounter? Septon Meribald. What does Meribald do? Wanders the Riverlands administering religious services. What is one such service he administers? Marriage.
And of course, the author had ample opportunity to say there were no more recent instances of polygamy, when someone actually asked him about it. He didn't. He actually left it pretty wide fucking open.
On my end it isn't so much disdain (although I dislike most of the ironborn, but that's personal taste) as much as it is pointing out flaws or weaknesses that people miss. For example, the Unsullied victory at Qohor was pretty much entirely reliant on the Dothraki doing something stupid like 1. not flanking when they could have and 2. making the same idiot charge over and over again and expecting different results. Good on the Unsullied for holding, but against a more competent foe it would have been a different story. And of course, on the flip side, it doesn't speak very highly of the Dothraki that they underestimated their foe in such a way. We also almost always see the Unsullied in defensive positions, guarding cities or households or acting as police.
I also don't see the issue of pointing out that Dothraki would probably be inferior to armored knights when we have examples of knights in armor in the story defeating Dothraki fighters (Jorah in his armor comes to mind). The Dothraki aren't really conquerors so much as they're pillagers. They sack, raid, take what they need and move on. So using them in a conquest situation, where you need to not only take territory but hold it and administer to it, might be difficult.
Some people may unfairly disdain them, but for every one of those, there's another one who overinflates their strength. It goes both ways.
And I have never said or thought that the dragons are unstoppable. I think that's as ridiculous an assertion as you do.
Aegon getting eaten by a dragon or not proves nothing as to whether he's real. A Blackfyre would still have Targaryen blood, and people with Valyrian blood have failed to ride dragons before (Quentyn and Alyn say hi). As for out-marriage, Essos has more people of Valyrian descent for the Blackfyres to marry, so I wouldn't take it as a given that a Blackfyre's blood would be significantly more diluted than Dany's (who has Martell, Dayne and Blackwood ancestors in recent generations).