Hiccups and Astrid Kiss.

Stoick gives Hiccup a Viking helmet made from the breastplate of his mother's armor. Hiccup says "Thanks for the breast hat." Nothing too explicit or dirty, though.

No category for this, but there are some crude references to underwear and the like.

A character hits another one with a shield, and she says "now there's blood on it."

A large dragon eats another small dragon (a Gronkle). This accounts for one of the three deaths in the entire film, the other main one being the Red Death itself/herself when Hiccup and Toothless take it/her down into an explosion. A third, minor death (one Zippleback) occurs shortly after the Gronkle's death, in the same way the Gronkle died.

When Hiccup attempts to demonstrate how his bolas cannon works to Gobber, it malfunctions. Gobber dodges it and the item the cannon shot out flies through the window and hits another Viking outside.

The first time Astrid says "That's for x, and that's for y," she knocks Hiccup to the ground and thumps the butt of her axe on Hiccup, presumably on his stomach. Astrid has a running gag of punching Hiccup in the shoulder before negating it with a corrolary nice thing to say.

A sheep is killed in the beginning

There are several action sequences involving warriors in combat with dragons, mostly dodging the dragons' attacks. Some mild violence with crude weapons which mostly end up hitting inanimate objects. No blood ever shown. One character talks about his dragon conquests which cost him body parts. He has a false foot and a hook for a hand.

Dragon violence involving breathing fire.

Before the Vikings attack the dragon's nest, Stoick says "When we crack this mountain open, all hell is going to break loose."

Viking drink from large mugs in celebration, implying beer or ale.

A dragon regurgitates half of a fish to share it with a human. The human takes a small bite from the fish and appears uncomfortable as he swallows. May gross out some viewers.

For everyone.

The movie starts with dragons attacking a village at night. Dark scene with fire and explosions.

Fighting with/defending against large dragons in an enclosed arena.

The Night Fury roars at Hiccup, while Hiccup looks away. This is unexpected and this is mostly like a jump scare.

Toothless brings Hiccup and Astrid to the dragons cave, inside there is a big hole where the dragons are dropping food in it, a gigantic dragon jumps out of it and eats one of them, this could be scary to some kids.