These strike me as tactial questions when you should be asking strategic questions.

• How will you structure things library-wise?
• How will the libraries be used?
• What abstractions do you want to depend on? (Depend on abstractions, not details)

I think if you answer those questions then what is good design will become more aparent. Put the strategy first, and then let the tactics match the strategy. Otherwise you will have no strategy and bad design no matter which decisions you make.