Ok., I can answer some parts of my questions. I looked in the code of David. Nice code and good to understand.
Roadrunner seems to store the imported Pois in a sqlite database. So I think the will be available permanently.
My other internal question was considered about keeping display on. Roadrunner keeps display on when it is on alert.
So I will give Roadrunner a try.
Thanks to David for this nice application.