Yes, you'll end up creating a new object for each function of the plugin - one to launch the default player, one to play, one to stop, etc. It sounds like it might be a lot of work, but it goes pretty quickly if you finish off one completely, clone it, and then make a couple of modifications as a way of creating the rest.
As far as creating the controls, you can do this several ways that I can think of. One way would be to have a background image that's just a layer (I think you've already got this part). Next, use your paint program to "cut out" portions of the big image. For example, you could copy the portion of the background that contains the play button. This portion would be saved out to a new file and used as the image for the play control. If you place it in just the right spot over the background image, it will "fit" into the image perfectly.
You could also create a dummy layer like you alluded to. Simply make an image that's just large enough to cover the play button. If you make it 99% transparent, it probably doesn't even matter what the image looks like. Again, you'd create a new object that's responsible for the play function, and then assign this image to it. One downside to this method is that it's sometimes a challenge to work with "invisible" objects - they're hard to find! You'll end up using the object browser quite a bit
Of course, if you go this route, set the alpha blending high while you're working on the object (so that you can see it), then turn it down when you're done tweaking it.
I'd suggest using the first method that I described above...
