FIRST and VEX are fairly large competitions, so it should come as no surprise that people have literally written books on how to participate. My favorite book aimed at FTC is FTC Robotics: Tips, Tricks, Strategies, and Secrets. They've made several editions of this book; although it's not a structured curriculum, it is a great guide and a must have for a team.
If you're looking for inspiration, but not necessarily a guidebook, the FIRST Robotics: Behind the Design books (editions for Aim High and Rack 'N' Roll), which document the designs of world-championship bots from those years. It's not detailed enough of a description to copy their work, per se, but they do present some very interesting concepts.
Some non-FTC/VEX specific books can be helpful, too. For instance, I found Building Robot Drive Trains to be a helpful book, and should be reachable by any highschooler with a working knowledge of trig. A detailed-but-good book is Constructing Robot Bases that describes different methods of chassis construction. Some of it is not so applicable because it assumes you have access to any and all materials.
You've already found the VEX curriculum; another great resource are the CMU curricula. Since I'm VEX-centric, I know about the Cortex Video Trainer. I'm sure there's something similar for the TETRIX platform.
Another answer mentioned Coursera's Control of Mobile Robotics course from Georgia Tech. This is an incredible course (I took it my senior year in high school, and have actually met the professor who created it), but a working knowledge of the basics of differential equations is pretty much a requirement to understand all of it... so that's most likely out of reach of most high schoolers. Some of the early videos could be helpful to your programmers, but it doesn't discuss construction/design at all. I can't speak to the edx course (I haven't taken it, but might now that I've heard of it), but I'd assume it's probably in the same vein of prerequisites.
One of the best ways to learn how to build competition robots is to read blogs and websites made by competitors. For a taste of blatant self-promotion, my team's website has a series of tutorials on how to certain VEX components. Xander Soldaat's blog, BotBench, is the source for a lot of ROBOTC related content. Find out who won the World Championships for FTC last year, and look up their websites; the best teams often share their secrets.