Q1: Depends on your lake/river/time of year and patterns the fish are holding. I fish a lot of shallow water 4ft or less, my Side Scan is more of a toy than anything most of the time.
Q2 and Q6: Yes get a contour map of the lake to find starting points. On the map you will see lines with numbers on them. If you find where the lines are spread out you have a gradual fall in the depth, or it's a flat. If the lines are all crunched up and there's a bunch of them, that's a drop off. Take early summer patterns into considerations for now. The fish are transitioning from the beds and going to their summer haunts. With that being said find a point with a hump on the end of it next to a steep drop off, if you can and they exist. Use your finder to find bait or bass on the hump and fish it with your confidence baits. Some like crankbaits, some like big jigs or plastics, find something they want and go from there.
Q3 and Q4: Look for the arches. Now you can turn your fish ID on, however once you start getting the hang of your electronics you will find they perform better without the ID on. Look for the fish, a good thing about the electronics is they not only show where the fish are, but where they're not. Just keep in mind the image you're going to get is a cone directly under the transducer, whether it be in the stern on on the TM. So, if you find some structure you may want to give it some time because your sonar may have missed the fish.
Q5: Baitfish. You will see the bottom clearly, then suspended somewhere between the bottom and your deucer you will see a blob of 'something'. In no real shape, just whatever ball the school is in at the time. That's your baitfish. If you mark them, but no individual fish, fish it anyways. That's when you can guess that your sonar cone has missed the individual fish. Be aware of your surroundings, sometimes a tree branch will be suspended and you only catch the end of the laydown. It will look exactly the same as the baitfish.
In the attached picture (I know not your model, but it had the best screenshot for me to describe). You will see many fish with the 'arches' suspended above the cover on the bottom. In addition to that you will see a ball of bait slightly suspended off the bottom. Notice how it's not attached to anything like the structure is near it. The structure normally will look attached to the bottom. On the right of the screen about mid way up you see a random blob under a fish, that is more baitfish being harrassed by probably both fish above and below it. Notice the depth change from 54 ft to gradually shallower. That will be where the contour lines on the map seem evenly spaced, not scrunched together, but moderately close, depending on how many feet are covered by each contour line (that would be covered in the map legend on whatever map you buy).
I'm no expert but I hope this helps.