1. Who will actually write the code?
Agencies win pitches with senior people and deliver with juniors. Ask the name of the person writing your code. If it is a different person from the one in the room, you have your answer.
2. Where will the source live, and who owns it?
The right answer is: a Git repository in your company's account (GitHub, GitLab, Bitbucket), with the developer granted access. Anything else is a soft lock-in.
3. What happens to the accounts when we part ways?
Domain, hosting, database, email, analytics, any third-party API keys. All of these should be registered in your business name from day one. Ask specifically.
4. What is your fixed price for the first release?
A serious developer will scope a first release, fix the price in writing, and manage changes through a simple change note. "Time and materials with a rough estimate" is a red flag on a small project.
5. How often will I see working software?
The right answer is every week or every two weeks, on a real environment you can click, not a slide deck. Anything longer and you are buying on trust.
6. What does your testing look like?
You want to hear about staging environments, automated tests, manual checks, and a staged rollout process. You do not want to hear "we test as we go". Everyone says that. It means nothing.
7. What happens after launch?
Good developers offer a light monthly retainer covering hosting, monitoring and small changes, on a short rolling term. They do not lock you into a year. They do not charge a penalty to leave. You should be able to walk any time.
Bonus: the tone test
Read their last few emails back. Is the English clear? Are the numbers specific? Do they sound like the person you will speak to for the next six months? Instinct is a fair signal. Listen to it.