About the rectangles - have you tried drawing them on a new layer behind the one where your people are? That way, you don't have to cut the rectangles apart.

One good thing about using a vector program like Xtreme is you have the flexibility to move individual objects behind or in front of other objects. You can drag the shape below another using the Object Manager, or select the shape and use the keyboard shortcuts to move them:

Control-B - moves shape to back of layer
Control-F - Moves shape to front of layer
Control-Shift-B - Moves shape behind one step
Control-shift-F - Moves shape forward one step

I looked at your file, and I noticed that you have your background rectangles filled with white by default, which means if you put something on a layer below that, you won't see it.

You can set that so shapes have no fill. Make sure nothing on your page is selected, and left-click on the box on the color line that has a criss-cross pattern on it, next to the little eyedropper. That sets the shapes to have no fill.

If you want all your shapes to have no fill by default, go to the Utilities menu - Options, and click on the General Tab. Check "Give new objects most recent attributes". Then, any shapes you draw should be clear by default.

Now, if you make a new layer and drag it below your lines and start making colored shapes, they should show up beneath the lines.

It's true what you say about drawing people - the lines aren't always closed. That's why Bob Hahn did his coloring on a separate layer underneath his line work in his video.

I hope that helps.