I agree with Cindy, there is no need to give too many details regarding your current 'startup' state of your business or even the fact that you're still working full-time. By all means, let them know your availability but no need to give them all
She is also right in not letting the client dictate the terms of the confidentiality agreement. This is your business, you should be dictating the terms of the agreements.
As far as giving too much information, I always lean towards what my Dad used to call 'overanswering' or as Cindy refers to as 'under promise & over deliver'. So, your response obviously shows a great deal of familiarity with the industry and I think that is great. It demonstrates to the potential client you know your stuff, so that is a definite plus!
Good luck, I hope this interest develops into your first client!