I am new to the world of small foamy planes and their setup. One of the things confusing me is servo's!

So I'm putting together a Squall that calls for 9-10gr micro servos. I had some Voltec micro servos left over from a Precision Aerobatics plane and thought all was well. Then one of the servos tested bad. So I order a Hitec HS-85 that was suppose to be a micro servo; except it's twicw the size of the Voltec servos

Here is my BIGgest[:-] question _ when a plane calls for a 9-10gr servo, what is that referring too? I suspect it refers to servo weight, not torque; am I correct?

2nd question: it appears to me that there are several sizes of what companies call micro servos. How do you determine what physical size of servo is required?
thanks.