Although not really essential, I will say yes to all of them and I'll make a case for the 30 amp to 50 amp adapter.
This adapter will allow you to connect your 30 amp service cord to a 50 amp receptacle at the campground pole. Why do this? I have burned several 30 amp male plugs while connected to the 30 amp receptacle at the pole. I have found that at most campgrounds these receptacles have been abused and overused for many years and will not make a good connection with the RV service plug.
Campground owners are too cheap to fix this unless the pole burns up! In my experience, most 50 amp receptacles at the pole are newer and less used therefore make better electrical contact. The $10 bucks or so that I spent on the adapter has paid for itself many times not counting not having to deal with a burned service plug while camping.
Check the condition of your 30 amp plug blades and you will know what I am talking about.