Dream Drop Distance How do Spirits and Abilities work?

I am really confused on the spirit combat system. I just restarted the game because I accidentally pushed my way through with out leveling Sora or Riku with my spirits, etc. I know it's a stupid mistake. xD Well anyway, I am trying to level up my spirits and level up Sora and Riku's defenses, etc. Once you obtain a ability with (LP) Link Points. Will both of the abilities you chose go to Riku and Sora? Such as Defense, Attack Haste, Magic Boost, etc? Or will the ability only go to one character? I am really confused on the subject. Also as for Riku's Dark Slide/Shadow Slide move, How do you obtain it? I've tried but nothing worked. Also if you keep getting abilities like Second Chance, etc will it boost its ability or would you just have to keep one ability? Like Once Second chance for Sora or Riku, etc. I'm highly confused on this part. I hope someone helps. And what's the fastest way to gain LP for the Spirits? Will your spirits attacks and such be apart of Sora and Riku? etc. Like I said, I have no clue what to do here or how the abilities work. Thanks if anyone's willing to help. :)

 

Even though you're banned and you won't see this message, yes, it DOES go to both characters. Just in case any guests needed help. On the subject of if you get a second ability if you earn another one, it depends if you already maxed it out, like you can only have 5 HP boots and 3 Attack boosts, etc. And the fastest way to earn LP is to give them toys/food.