Current regulations only require that you take the knowledge test. If you're already a certificated pilot, then a CFI can sign you off once you've passed the test and you get your new card. A FR keeps it current. Otherwise, you have to take the test at a facility every two years.
No practical experience necessary.
If you want to get in the business, cheap drones are cheap. Payloads/sensors are where things get expensive... well, that and adhering to the requirements of whatever client you manage to snag. Lots of competition for low-hanging fruit. Higher-risk = higher pay, but the equipment/training/compliance costs get astronomical pretty quickly.