Re: steering problem
Don't know Mercs but there should be some zerk fittings on the engine, I would start there and make sure it is greased right but as the others said, if this is a new boat under warranty you don't want to touch it since that may void your warranty.
Get it to the dealer and let them solve it.
If not there are only 3 parts ot a steering system, the head, cable and pivot pin on the engine, first I would make sure the engine mounting bolts haven't come loose, next is to disconnect the steering cable and make sure it turns freely with the engine not on it then check to see that the engine turns easily without the steering cable attached.
If you haven't isolated it after that I don't know.