Where’s the Move Trainer and Move Deleter

Once you've received the roller skates and unlocked the northern half of Lumiose City, you can learn the tricks from roller skaters in the area. Here are their locations:

Trick #1: Backflip - By a tree just outside of the Hotel Richissime on North Boulevard.
Trick #2: Parallel Swizzle - Inside an office building on the western end of South Boulevard.
Trick #3: Running Start - By the monument in Vert Plaza.
Trick #4: 360 - Inside Cafe Rouleu on Estival Avenue.

With all four tricks learned, return to the man in Lost Hotel. He will let you through to see the Boss, who teaches you the game's fifth and final roller skate trick - the Cosmic Flip.

Source here.

You can only gain affection in Pokémon-Amie by playing with your pokémon and feeding it. When you get enough hearts, the benefits are:

• Increased Exp (1.2x, to be exact)
• Increased chances of dodging a move
• Chance of enduring a move with 1 HP
• Chance of getting rid of a status at the end of a turn
• Increased chance of getting a critical hit

However, happiness (friendship) is earned by leveling it up, giving it certain berries, going to the massage person, and walking around with it. From what I know, the effects are:

• Return does more with more friendship
• Frustration does more with less friendship
• Your pokémon evolves with enough friendship

But however, from my experience, Pokémon-Amie affects happiness as well. My little brother always played with his Kangaskhan and Return was one of its strongest moves. Whenever he got too many Poké Puffs, he would go to his Pidgeot and throw all of the Poké Puffs away because he thought it was funny. When he taught it Return, it didn’t kill a Caterpie. I’m not lying! The Pidgeot’s Frustration was like the Kangaskhan’s Return. What I concluded from this is that Pokémon-Amie slightly affects happiness as wel.