Limited access to 'Edit' Commerce Order & limit line items to only 1 type
While it is possible for you to add those fields to the order, you should really create a new review content type and then use those for your reviews and then use an entity reference to connect the review content to the order. In the future, if you did want to allow line items to have reviews, you could then just add another entity reference field to the line items and you can reuse all of the UX you've built for the main review form for anywhere else.

Furthermore, by using a reference, you're not limiting yourself to a particular type of form. If you ever wanted to differentiate between certain types of services and provide different review criteria, you can much more easily do that with new content types + entity reference.

Brief overview of steps:


Create a new review content type with your fields and fivestar info.
Create an entity reference field on your Order. I believe you can use Entity connect to have it show a "create link" if no reference exists.
If that doesn't work, you can use Views to make it so that a user can only connect the entityreference field to orders that they own.