Do not put that guy in your reef!!! He will tear it apart. The red crabs with spots are indeed more agressive, but these little guys like you have in the picture are often from ***** and really are capable of tremendous damage in a reef.
If fish only then go for it they are wonderfully active and have demonstrate loads of personality.
As for the anenomes I dont know what kind, but they are always on the shells of these crabs. You can add a new shell and let the guy swap out and then do further research or remove the anenomes at leisure.