J-BusinessDirectory - Questions before purchasing this component

Hi

I have had a good look at this component, and am interested in this for an intricate and very important project I am about to embark on, which will have in excess of 150,000 records.  However, I need the following questions answered prior to committing to purchasing this:

1. Once the component is purchased, is support free of charge thereafter?

2. The CSV Import feature.  If one csv file of, say, 1000 records is imported, and an additional CSV file of 1200 records is imported at a later stage, will it ignore duplicates, and only import the new/extra records from the csv file?  If so, what field is used as the "key" field to identify the duplicates?  This is most important.

3. Is automated billing included for business owners who sign up to whichever package is included?  Is invoicing integrated and can invoice layouts be modified?

4. Is the EUR currency included? 

5. Additional fields/custom attributes - show in filter - does this work? Didn't appear to on the live demo site

6. Existing fields - is it possible to prevent a registered business owner from editing or changing an existing field? I know it sounds odd, but I don't want users to be able to amend the telephone number of a listing they "claim"

7. Is it possible to integrate/link  3rd party API's - my project is a restaurant directory but I need to be able to include (for certain businesses), a third party booking/reservation <div> or similar to some listings.

8. If J-Business Directory is installed using a fully responsive template, is the component fully responsive too?

9. Multiple filters & searching (frontend) - on the live demo, the filter search doesn't appear to include custom fields/attributes - please provide me with a detailed description of how frontend filtering works.

10. Is the component compatible with, or does it link to any Joomla Mailing components, for newsletters etc. I would have a requirement to provide newsletters to customers and business owners, separately.

11. Looking through your support forum, you do say that customised work may be done by your technical team - please provide me with overall costs for same and additional info. Feel free to email this to me privately, if required.

Many thanks