Concerning Gendry i wonder why they brought him back now all of a sudden.. in past seasons he had his place as Melisandre's ritual victim due to his bastard nature but now? For me it can only be to forge Lightbringer in season 8 (if the show goes that route at all), the magical sword that the champion Azor Ahai wields.
However it was very cool to see him again and especially wiedling a warhammer.. the weapon of choice of his father (either by chance or choice, it wasn't made clear in the show).
Yes, I realised I had missed out Gendry's forging skills being of importance so I edited my post. I must have been still editing it while you posted this. However not much importance was been put on Lightbringer in the show. I think they might opt out by making Dawn into the Lightbringer. In the show there is no mention of Dawn being returned to the Daynes so Ned might have kept in and it might be in the Crypts. They did make a strong point of showing it leaning against the bed in the Tower of Joy.