I really do not understand where your issues are: the only difference between the Freescale and Analog accelerometers in the example you gave us are the signal output.
The first one (MMA7260QT) is linear, the latter (ADXL202) is PWM. I don't see where your problem is.
By the way you gave us an obsolete example; the correct and updated web address is: https://www.kerhuel.eu/wiki/index.php5?title=Miniature_Inertial_Measurement_Unit_-_IMU
Obviously you didn't take any look at the correct address, otherwise you will have found lots of info (I think even Simulink and Matlab code!!!).
There is an implementation of a 6 DoF sensor (see end of page) with sample code too!
If your only problem is "how to convert a PWM signal to something you can read", please tell us what you have done so far to read the signals and what type of problems you have encountered in your implementation.
It also would be kind if you will describe what you have done so far in your experimenting with accelerometers and gyroscopes: from your answers it seems to me that you have to dig a bit deeper on the argument.
1. You can either measure i digitally with a timer or as an analog voltage after avaraging it by a low-pass. Digitally measurement can be more accurate but requires more software.
2. It's a measurement range for rotational speed. You also may want to ask what's a gyroscope?
1) programming a microprocessor does not require too much electronic knowledge: I have never used AVRs but a quick look at ATMEGA16 data suggests to read thoroughly the 16 bit timer1 chapter.
BTW, are you sure this device is enough for your requirements? Maybe you will need a more beefed up device (more input capture/timers)...
2) such a question suggests you have to study in more detail the gyroscope workings. BTW, it is the maximum angular "displacement" that can be measured in one second.
I'm sorry, but from your questions it is clear you have not yet understood the difference between an accelerometer and a gyroscope!
I think any answer will be wasted until you will grasp those fundamentals.
BTW, why do you insist to try to use devices (ADXL202 and ADXRS300) which are becoming obsolete?
It means that you have to study deeper the definition of gyroscope: if you will do it, you will get the answer by yourself!!!
BTW, I and FvM have already answered your question but you didn't realize it!!!
As I wrote, I don't like to give precanned solutions: you have to understand what you are doing... but from your questions it is clear that you have never taken a look at the references I gave to you.