Where could I rent a trailer hitch,, trailer arms, brackets

You can't rent a trailer hitch. It's part of your vehicle and there's wiring that needs to be attached to your vehicle to make the electronics on the trailer work.

I dont know? Just buy the dam thing you cheapskate

A hitch needs to be mounted into your vehicle. It will depend on how much it can pull to determine the size. Of you are renting the other items should come with it.