That's where Loras gets greatly wounded right?

Catelyn was dead and rotting in the water for days, though. Jon will permanently have the wounds when he died, as those reanimated by fire never heal, much like Frodo never fully healed on LOTR, a fact of the bittersweet Tolkien ending Martin has praised a few times before. It would be cool if those wounds had made him on permanent pain and somewhat affected his judgement, or if he had forgotten someone of his family, but since the series follow the broad outlines of upcoming books, I doubt we'll see anything very drastic. Either way, his life is probably linked to the existence of dragons right now, since fire magic supposedly came from them.

you are correct, Euron and the Ironborn start raiding the coast of the Reach while the Redwyne Fleet is at Dragonstone so Loras leads a reckless assault to end the seige quicker and free up the fleet.

Cersei is just pure evil in the books. I love how they portray her in the show, she's much more human and broken. That character was bound to make stupid mistakes after stupid mistakes - She does not see the value of Dragonstone, she's using it to send Loras to his certain death (and it almost worked). Same way as she did send Mace to the Iron Bank in Season 5. She only understands the ramifications of her actions in hindsight.

It's mostly the budget.  They would have needed to hire way too many actors to cover everything in books 4/5, not to mention that books 4/5 weren't particularly good anyways. Though Season 6 was a huge step up from season 5, and it will only get better considering they've killed most of the other characters lol.

I find it so interesting what gets people hung up on certain things. While they're able to capture so much detail, people seem to want the show to play out like an encyclopedia without any urgency.

Updated the OP with a chart of the episodes and their average rating from the polls put up in thread. Dragonstone got 7.2 (thats including the twenty scored as 1 which were given (i think they were just troll posts but they're included anyway.
ill post the second poll closer to ep 2 air time.

He's also a Targaryen by blood so there are two reasons for the dragons to take to him. I suspect one or more of the dragons is going to follow him after he meets Dany and heads up North. I also think one of them is going to die at the hands of the Night King and be raised as his personal Ice Dragon (GRRM did write a Westrossi kids story about an Ice Dragon).   

New poll up ready for when you've watched it.
Also get ready for the return of Gendry! the third Targaryen, I feel sure this is going to happen.

That episode was amazing.

I'm a little confused.
Pretty sure one of the sand sisters died. Did the other one die as well? Were they hanged at the boat?