If I buy a boat already docked at Shoreline Marina, may I continue to occupy that dock, or do I have to pull it out and find a new home for it?

No. You have to apply for a slip in your name. Depending on the size, there may be an opening or you may be on a waiting list for months/ years.

I agree with Todd.

I have no idea. The previous two comments should help though.

More than likely the marina office would allow you to keep the current slip as long as someone with higher seniority hasn't got a request in for that slip, in which case they will require you to move to another one.

You would be able to leave it there, providing you make the slip payments 😉