Apart from the draw distance, there are only two levels with significant extra content. Pier is one, i forget the other.
Scanned your posts twice but still didnt notice if you are running Nvidia or ATI?
Nvidia was official supported in patch 1.33, the leaked version of 1.4 had ATI support, although i here some guys have it working on ATI with 1.33.
Assuming you are patched to 1.33:
To enable HDR.
1st turn off AA.
2nd Set graphics to High or Very high (Whichever displays SM3.0 you can see this if you type \r_displayinfo 1 in the console \r_displayinfo 0 to turn that display off)
3rd In the console type \r_hdr(then hit tab) it will auto complete "\r_hdrrendering" complete the command by adding a number from 1-11
eg \r_hdrrendering 6 (the number set a coarse control on the degree of brightness and rate of adjustment)
If you play online, things to remember with both the 64 bit and HDR:
Always set HDR back to 0 before going online, the majority of servers will kick you for having it set to any other value.
Always follow the instructions in the file you down loaded for removing two files before you play online, i think its objects2 and textures3, or again you will be kicked from servers. You can simply replace them once you are done playing.
If you have any other problems you can always find help on the Ubisoft Far Cry forum
HTH
CuZ