Friend or foes?

Hello, new to marine keeping always had tropicals, so i am in the process of setting up (approx 9 month) and i have some critters that are keeping me up at night i find fascinating, and any help to id these chappies would be most appreciated,thanks

The brown like shrimp there seems to be loads of them in various sizes scrambling all around my live rocks.

The white and pink spotted snail with little white mite creatures running all over it, moves more like a slug if it helps.



Hope the pics okAttachment 112570



Attachment 112571 thanks again.