Re: How intense should Crossfit be?
A good rule of thumb is to check the scores in the comment section and find an average. Scale the workout so that you're within that range. It's obviously not scientific, but it's a good way to get a feel for where you should be.
For an idea on Fran, try what we call "skinny fran" ... do the thrusters with a broomstick and jumping chinups instead of full chinups. That way you go through the motion with less load and get an idea of what's "realistic." Then slowly increase load while staying relatively close to your skinny fran time.
And yeah, brand x is awesome for scaled WOD ideas!!