Congrats on your new vehicle.
It is possible to get a swivel for double passenger seats for many vans.
You should be able to get a double seat easily and sell your single one as they are in demand.
For this and the other bits you mentioned I would recommend finding someone local to you.
Either a conversion company or a specialist individual.
This will give ensure you can return to then to have anything tweaked after the work has been done, and means you have to travel less far to get it done.
Try a Google search for your area to find someone.