I am an experienced Unity developer, having authored or collaborated with several applications for 360º vídeo visualization and VR games. I have been working with clients all around the world for years, I'm used to self-manage and to articulate with different time-zones.
As for the project, I can help you with bugs, since I've been using Unity since version 2 and coding C# since .Net v 1.0, so I know all the tricks on the book ;)
As for the milestones, I propose a kick-off fee of $1600 USD, after the payment is cleared, work starts immediately.