I will comment on the nurse aspect in the US. The minimum educational requirement is an associate degree (ADN) which takes 2 years to complete. The next level of education is a bachelors degree (BSN) which takes 4 years. Both associate and bachelors prepared nurses take the same licensing exam and have indentical clinical roles. There is a push for bachelors to become the mimumium entry and many large academic hospitals will only hire BSN new grads. Also, many managment positions require a BSN. Once a RN there are various speciality certifications you can acquire in ICU, Cardiac, Neuro, etc which usually require a year of experience and an exam.
RNs are rarely used on ambulances. Some states allow RNs to practice within their scope on ambulances but that is rare outside of hospital to hospital critical care transport. RNs do have presence in helicopter EMS. This requires multiple (5+) years of ICU/ER experience and multiple extra certifications. Fight nurses have a broad scope including all the drugs you mentioned, intubation, central lines, and chest tubes.
Our CRNAs require a 2 year master degree with an option of adding a 1-2 year doctorate after your 4 year BSN. CRNAs in some states are able to function as independent provides and manage patients autonomsly.