Yes, some are difficult to find. You can always go back and find them.
As long as you're willing to travel back to the stone, you can get the skill at any time.
they teach you hidden skills
Go to the hidden village.
You get it from the lady in the hidden village when you show her the domain rod.
You show your Dominion Rod to the lady in the Hidden Village.
The gorons find it for you and marks a dot on your map search near Hyrule field
she does. Defeat the 20 monsters then she gives you the charm.
In The Legend of Zelda: Twilight Princess game, you need to have completed certain missions in the game in order to get to the hidden village. Once you have completed all the missions you need you will have help breaking the wall.
The second hidden move (shield attack)'s howling stone is on Death Mountain, while the wolf itself is in Ordon Spring.
That depends which wolves you've already found and how far you've gotten in the game but i think you're talking about the stone in the hidden village.
they are hidden in rooms you have already been in so look everywhere you'll eventually find them
You have to find it in the temple of time, which is hidden in the sacred forest. if memory serves, you will find it after you defeat the mini boss.
There's a multitude of things you can do after you've beaten the game! Explore the different areas and find hidden passageways. Theres many hidden things lurking about in every world, its fun to find them all!