I worked with Roku before. There are quire a few pitfalls with it... but those can be avoided when you know what you are doing.
I see 3 steps in this little project:
1. We would need to first determine the ROKU app screens that you need, and discuss the API endpoints you provide. By the description of the project I suspect there will be 4 or 5 screens to be developed.
2. Then I will work on developing the application, with your support for the backend.
3. The last step would be to test it on your end, and get your feedback. With that feedback I can work on the loose ends / bugs.
Concerns:
1. Roku will soon releases its 7.5 software version, which could create problems with any existing channels. It will probably not be before the end of the year but it is something to keep in mind.
2. Roku offers ads support, so if you want to develop this in the future we can analyze that for you as well, after the project is complete.
3. Roku has a lot of device models on the market. I will not be able to get them all to test the channel. So I hope you have them all to do it.
4. I will not be able to work full time on this project, so you will have to be patient with me, if you choose my bid.