Agree with Shaun's answer: Infrastructure and KPI's are not necessary until your organisation gets to a size, where the management team does not know everyone.

If you want to measure engagement, build a process, that ensures that managers regularly interact with all employees once a week, month, quarter - depending on your needs for dialogue. And have the managers report back to CEO how things are. I think you will learn more instead of just measuring. Measuring is easy - changing processes based on feedback is hard, because it is about culture. If you ask, be prepared to change based on the feedback.

Employee retention is easy to measure by comparing your staff month on month on some ID-key (employee number, social security number or similar). If you are there in one month, and not in the next, you are gone. Reverse means you are new.

Let me just finish this by commending you on your focus on the softer side of things. I think it is good, and I am sure by focusing on it, you can create an environment, where people are happy to work and will be engaged.

If you want to talk more about this, keep in touch - call or mail.

Best regards
Kenneth Wolstrup