Hello,
It sounds like you are going through, or are about to, go through the sales process, I would suggest you work with an Alfresco sales or sales engineer - they will help you identify which questions to ask.
When you say "configuration" - I am assuming you mean customization? Truly configuration questions can be answered by support - this is what part of the enterprise subscription is about.
In general, the approach you outlined is good (including the bullet points) - there is really no way to avoid having to sit down and figuring out your requirements- you know your business much better than any consultant does (unless you pay them a lot of money to do a thorough analysis and requirements gathering of course). Other things you might want to think about off the top of my head:
Which App Server are you planning to run this on?
What is the deployment architecture (clustering, security, etc)
Are you planning to integrate Alfresco with any in-house tools or other software?
What is the load going to be?
Lastly, this is a collaborative effort - the partner you'll work with will likely ask you to provide information so they can give you an accurate estimate.
Jean