Will you be able to review specific topics in Firecracker MD and Firecracker DO?

Yes. Both Firecracker MD and Firecracker DO will have a “Study Something Specific” feature, which will allow you to launch review questions on every level of the content tree (including the topic level). In fact, you can even choose what you want to review more specifically by filtering certain questions, such as those you've never seen, those you have low or high review score on, etc.