Your questions aren't nonsensical. They're metaphysically speculative instead of fact-oriented. The difference is as follows:
- What did Kant believe according to neo-Kantians about the rational metaphysics of Descartes in the Critique of Pure Reason?
- What do you believe is a the best metaphysics?
The former question is essentially a question that draws on definitional and encyclopedic information and resources. Many Kant scholars have read CPR, and one can find entries in the WP, IEP, SEP, and EoP on Kant and transcendental idealism. This is a question that asks a fact about philosophy. This is descriptivist. "Philosophy is..."
The latter question is a question that asks someone to deliver their personal views on philosophy. This invokes personal views and normativity. This is prescriptivist. "Philosophy ought to be..."
This is the fact-value distinction. Of course, someone who is highly knowledgable about Kant does introduce normativity by way of selecting interpretations, references, and might even drop a comment or two about personal views, as long as there is a measure of epistemic humility.
So, take a look at your three questions, and ask yourself, are they questions about facts? or questions about values? If they obviously fall in the latter category, then they are not nonsensical, just ruled out of bounds by the community.