TMS320F28334: IQ MATH Understanding

Hello,

I was checking HVACI_SENSORLESS_2833x example in CONTROL SUITE. In that Project I have doubts that I want to ask.

Which are as follows:

1) I have read IQ math Guide in Control Suite and from Internet about Q Notation but yet I am not able to understand IQ math method in Given project.
I understand that Q notation is means fixed point value. I also read its doc in control suite. Can you please give me info about this in easy way with example.

2) There is macro in IQ math header 
#define   _IQ24(A)      (long) ((A) * 16777216.0L) 

I don't understand what exactly this macro do. I understand that it is convert value to Q24 Value but what exactly its purpose that I am not able to understand.
As Q24 has integer range -128 to 127. Will this macro not exceed that Q24 range so How this is Q24 conversion?

3) I have mcu F28334. It has FPU. What changes I should make to use this code for F28334? I know there is Float MATH option in header file. Should I open only that macro or any other changes need to be done?

Thanks & regards.