Okay, lots of questions here. I'll start by reviewing.
1. Problem 1 was a strange graphics glitch. One component would not render. That is gone after restarting the computer which sort of indicates a graphics issue. Please report it again if you see it again.
2. Canvas is not decal. Yes there's an option to render canvas, which is off by default, but it's not supposed to be used as a decal. Canvas is a backdrop you can resize and use as a reference image to draw sketches on top of, or place objects around. Looks like you worked this out yourself.
3. Last is a bug related to decal and derived parts. I'll log it. Derived components are not honoring "do not chain faces" option in the decal in the source design. It should.
Advice: Do not use derive for workflows like this. Here's why.
Derive is for using a source object as a starting point for new parts.
- When you derive into a design, that part can have more work done to it that lives only in the place where you inserted it.
- The source file can update and it will update the inserted copies.
- Any changes in the inserted design are re-computed.
Derive Workflow: If you wanted to put a different decal on inserted copies of the source designs in the assembly, and then render it.
If you want every inserted object to be a perfect copy of the original, insert a linked design instead.
- Inserting linked designs begins with a right click on the item in the data panel.
- It creates a linked copy of the source design.
- Any changes to the source design are then reflected in the inserted linked copies.
Linked-design Workflow: If you want to show several copies of any one object in the assembly, and do nothing but arrange and render them. This is what I think you are doing here.

Please let me know if this helps.
Phil Eichmiller
Software Engineer
Quality Assurance
Autodesk, Inc.