Some Prussia Questions

Hi, I'm getting back into playing Prussia with the new updates and DLC and I have 2 questions.

1. Do I have to research nationalism before resolving the schleswig Holstein question, or can I rush complete that journal entry?

2. Do I need to get all the small German states in Prussia's power bloc to form Germany?

3. If yes to 2, is the best way one at a time? I tried doing them in parallel but ran out of diplo influence.