Of course the answer to this depends on your terms and conditions. End of service comes when they pay the final invoice, but that of course depends on your payment schedule.
Closing Interview.
All you are doing here is giving them a chance to think of new things to add, problems for you to solve or issues that might otherwise not have been mentioned. You will definitely leave with a new todo list of fixes, otherwise the managers you are speaking to will feel they have not done their part.
Writing a document
All you are doing here is giving them material to question you, as well as spending time writing a document that may well be out of date before it is ever used. Never put anything in writing unless you are being paid to do it.
Training as part of handover
All you are doing here is offering training you have not been paid to do. Their analytics, logging into accounts etc is something you put in an email informally to whoever is actually going to need it. Not as part of a handover.
Post service questionnaire.
The only reason for this is to secure more work. People generally do not want to fill them in, will write or tick anything they think of immediately with no thought, and generally you are asking for criticism you probably don't deserve. Why give them food for thought about how you could have done something better.
What I would do:
In your terms and conditions you offer 30 days post launch support and bug fixing. If they do not ask for something, you do not provide it. You launch the site, give them the admin access, get your final invoice in, and sit back and wait.
After 30 days, you contact the decision maker and ask for a testimonial, or even better, write one yourself and ask them if it is ok with him/her if you use it. Often the decision maker does not have time to write these things, and will often agree to whatever you write. "We had a problem with our old site that the new site has fixed. We love the design and look forward to lots of success with it in the future, a big thank you to our designer and developer"
After 60 days (or sooner if post your 30 days support you get bug fixes or new feature requests) approach them with an ongoing monthly payment for website support. Here you can add in things like training on analytics, account security, administering the admin users, bug fixes, enhancements etc etc. Whatever you can think of where you add value without too much of your time. These support contracts soon become your bread and butter, and are so valuable that your actual website development and build costs are driven down in an attempt to get more of these support contracts up and running.
But initially, get the site live ASAP, get your final bill paid, and do not give your customer any opportunities to list more and more (often trivial things like "I am not sure we quite like the blue you have used") tasks for you to do before they hand over the cash.
Finally, you should have had a 'Schedule of Work'. If they ask for anything not on that, make sure you give them a quote for it before doing it. They should be paying for your time.
Paul.
