yeah, I think you have it right. If you have a question about any material or piece being legal, you should post a question to the robot section of the official FTC forum. Found here:
http://ftcforum.usfirst.org/forum.php The ruling by the game council that are made on the FTC forum are final and official. it is a really good idea to check that forum because the game council will make clarifications on rules throughout the year on the forum.