Assassins Creed 2 WATER and SHADOW problems

i have an issue regarding this game. i really need help

1. I read a lot about this in the forums and confirmed that this game runs with dx9 and does not support dx10 dx11 etc
Q: will this affect game play? i have an GTX 275 PALIT and set everything on MAX resolution at 1920x1080 no lag but
the SHADOWS are fuzzy and ugly moving weird, plus the WATER does not have any reflection ( again i max all the settings) and also, the puddles have no reflection too.

2. If ever the dx9/dx10 is the problem that caused these issues, can i get dx9 over dx10? BTW, my Vid card driver is dx10 but im using windows seven and it sez here that i have dx11 im a bit confused, anyway, i also read somewhere that i DONT HAVE TO OVERWRITE my dx10/dx11 with the dx9 because they are the latest and already updated.
But since i am experiencing problems with this i might give it a go.
Q: so is it okay to place dx9 over the other dx's? will i get my dx10 back after i do so? or the dx11 from my win7 64bit

3. Lastly, the most furthest theory i have is my procie, which is an C2D e7400 2.80ghz, which i think bottle necks my GTX 275 thats why the water and shadows effects have problems. BUT there is no lag what so ever. and i think this really aint the issue.

sorry about my confusing problem, thanks guys.

did you buy this or download it? also in the directory (where ac2 is found) is their a .exe for both dx 9 and 10, im pretty sure crysis had a thing like that or something along those lines

kindly go forth and multiply you thieving scum