All the advice you get here, much of it good, and all the advice you will get throughout the project (especially if you open source it on github which I highly recommend) is for you to assimilate and then build into your opinion.
Listen to experienced dev's telling you why and why not a particular course will work, listen to people here on the research and the unintuitive nature of suicide, but in the end this grant was given because you seemed to have an insight or a gleam in your eye.
Trust that gleam, and tell us lot to go hang, if you think you are being pushed into something that in your informed opinion is not the best for the app.
And remember, Its not the only suicide prevention work out there, so the weight of the world is not on your shoulders - your job is to do a good job and be proud of the work. Let the world decide if thats going to solve its problems or not.
Good luck and all the best