You can do either of those things.
- To check the color the mouse is clicked, just check
gfx.pixel(mouse.x, mouse.y). (Of course we will first need to figure out why PixelDisplay isn't showing up for you on Windows 7!)
- To define a "interactive spot" in the scenery, you could use the Bounds class. That lets you define a rectangle of any size and rotation, and then check whether the mouse is in it — for example,
if sofaBounds.contains(mouse) then...
If you're trying to make a point-and-click adventure, I'd probably go with the Bounds class. Make a little helper that lets you define where these bounds are, and a debug mode that draws them so you can see. And give each one the name of a function to run when clicked. Then in normal mode, you don't draw them, but you detect the clicks and run the corresponding function.
All this will be a bit of a challenge for a beginner, but take it step by step — and ask lots of questions — and you can definitely do it!