[fireftr18]

There are many artistic licenses needed to make a show doable. The characters are experts in everything to keep the cast small. They abbreviate proper procedure so that the show will flow and work in the time frame. You see the cast as first persons on the scene because it's about them, not initial patrol responders, paramedics, fire, etc. It's just assumed they were there and did their thing, then CSI shows up. Then visual items. An example is blood. In the shows, the blood is always bright red. In real life, it soaks into materials and the redness gets lost, pools of blood actually turn brown and get crusty. I figure this is done so that the viewer can identify the substance as blood.
The viewer needs to simply imagine that administrative and procedural tasks are done.
Your question about real life CSI. Every police officer is educated in basic crime scene investigation, every fire fighter is trained in basic fire scene investigation. Both are trained in scene and evidence preservation. Beyond that, it depends on the jurisdiction. Larger cities will have there own specialists, while smaller jurisdictions will rely on state specialists. As the complexity of the incident increases, the level of specialization of the investigators increase.