I have used multiple desktops for a long time, and find them absolutely necessary to organized work. First of all, forget what you were told by the tech. You can put as many or as few apps in each space as you want. And, clicking the icon on the dock of the app you want to use IS one way to switch spaces to the one occupied by the open app.
I use Spaces this way: Mail, Firefox, and iCal are each tied to a separate desktop - 2,3, and 4 respectively. That way, they can open and stay open while I work with my writing apps on my work desktop - #1. Switching to check a deadline date or respond to e-mail is easy -- I can hit the dock icon of the app I want to see, or do it by moving the cursor to the lower left corner, which activates Spaces on my computer - YOU decide how you want to switch spaces.
Only my Mail, Firefox, iCal and writing apps are tied to particular Spaces. In addition, my DragThing, QuickSilver, iChat, and iTunes are set in Spaces Preferences to open in EVERY window, so that they are constantly available as I move from Space to Space during my work day. All other apps open in whatever Space I am in when I open them. If, say, I open a PDF document I downloaded in the mail in my mail space -#2 - and then discover that I want to see it while writing in Space #1, I can easily drag and drop it from #2 to #1.
Spaces is only as good as your own understanding of how you want your virtual space organized. But once you devise an organizational structure that will work best for you, there is nothing better. Each Space is uncluttered and organized around a single task, and interactions between applications are coordinated for maximum efficiency. Try it, experiment with fixing different apps to different desktops or letting them open freely where they fall, and see what you think. It would be a shame to have such a great organizational tool on your computer and not use it!