Software development best practices for startups?

What are the best practices for software development setup for small teams?

We're a team of 2 and planning to expand to team of 5-10 developers.

As of now we've local development setup, dev server and prod server. We work on local environment and then test it on dev server. Both these environments have trimmed down version of database and media files.

Issues in existing setup -

1.Sometimes it becomes hard to develop and test features on development environments, because data is not same as production.

2.Performance testing is not possible on small database.

3. With changing schema, writing a script to create development database from production becomes obsolete.

4. Can't use production database as it has all user data.

5. How to share media files (few GBs)?