Sure, here are the rewritten sentences using question words + to-infinitives:

1. Susan still can't decide on when to study abroad.
2. Mary doesn't know how to get to the community centre.
3. The local artisans still don't know how to promote their products.
4. Could you tell me where to find the best speciality food in town?
5. James is wondering what to bring when going on a voyage.
6. Mark is thinking about how to improve his communication skills.
7. The team is discussing when to start the new project.
8. My friends and I can't decide where to go this summer vacation.