The lawnmower blenny and watchman goby should be a hardy addition to your tank. Just make sure you have algae for the lawnmower to eat. A yellow watchman goby is one of the hardiest fish I've had. I'd steer clear of the scooter blenny until your tank matures as they most often need to be weened onto frozen food or pellets (which may never happen) and need a lot of copepods or amphipods in the meantime.