Ask HN: How do you do quality control/assurance

We are a smallish tech team (11 developers) actively developing a product where downtime has immediate negative revenue implications.

It's starting to get difficult to ship changes without breaking something somewhere.

so my questions are:

1. what is your teams approach to quality assurance

2. what is your teams approach to quality control

3. at what point does it make sense to hire dedicated staff to handle these areas, and what skill/experience set should we be looking for.