Hi there mynetdude and welcome to the community!
Question 1: There is a useful mod that can help you determine what buttons you need to press for each action in LSPDFR
Here's the link to that mod:
Instructions are enclosed when you download it, in the README, on how to use it.
Question 2: You have to press "Y" to accept a callout when it appears in the dispatch box, and that should give you a location. If you so choose, you can way point it by going into you menu, hitting enter inside the map (to bring it full screen), and using "WASD" to move the cursor around. Once you have found a location, hit enter to way point it.
Question 3: To spawn cars from anywhere, I would suggest download a "Trainer". A trainer allows you to do different sorts of "administrative" actions, and is strictly forbided in multiplayer. Here is the link to it, and again, the method of installing it is in the README when you download this mod. Otherwise, you must go to a garage to get a car.
Hope that helps, and happy policing!