Just on your personality test point, the Birkman Assessment mentioned in the article is absolutely the pinnacle of personality assessment. It's not like the meaningless toy tests like MBTI/Hogan/16pf you may have experienced before. It covers the usual motivation and behaviour pieces but it is unique in surfacing the underlying needs and stress reactions which often have no correlation to your visible 'normal' behaviour that other people see. Really helpful in determining your approach to different members of the team as well as giving you the common language to explain your needs to other people. In short it's both insightful and actionable for you and your team members in your personal and professional life. Plus it's stable over time, so you take the assessment once and have 20+ years of value from it.
Disclaimer: I work for a company that uses the Birkman Assessment but no relation to MailChimp other than as a user of their newsletter services.