Start address is 0x400000 by default for windows executables.

But Eqgame.exe use ASLR, that means it can load in on any start address.
You will need to check the module list in your hex editor to determine the start address.

In your example it looks like it loaded in at 0x470000 (0xA0CAB1 - 0x470000 = 0x59CAB1 and 0x59CAB1 + 0x400000 IS 0x99CAB1)
That needs to make sense to you if you are going to locate offsets using a hex editor while eq is running...