Ask HN: Where can I find resources/advice on growing an engineering team?

Background: We are a funded startup with 4 engineers (15 employees) and I'm one of the technical founders. We have a large application and an important piece of it supports our on-the-ground team, so we're anticipating lots of pressure when we launch outside of San Francisco and begin scaling. We've been at it for a year so far and have a solid grasp on our product and user.

Some of the things on my mind are:

1. Prioritizing, organizing and distributing work in a way that makes engineers happy and motivated. The process we have now is okay, but I can't see it working if we had 10 engineers.

2. Define and maintain good (mainly consistent) code quality so new engineers can easily adapt and begin contributing quicker.

3. Implementing good processes for attracting, hiring, and onboarding engineers. Onboarding may involve documenting important business logic.

Any resources/advice would be helpful! I'd love to know how these things are done at growing tech companies. Any advice in general on growing an engineering team is a appreciated!