Prints without cropping (or with cropping matching my screen)

Having ordered a lot of prints from Flickr, I was disappointed with the degree of cropping that took place. I am shooting with a D300, uploaded a photo which shows on Flickr as having dimensions of (3337 x 2216) and when I ask for an 8x10 it cut off a fin which was close to the edge but not quite there (there is water between the fin and the edge of the frame). Obviously, if I was processing the image for printing and needed to crop, I would have cropped out the other side of the image which was just water rather than a pectoral fin of the shark.

I need to double check on my computer, but if it was not "cropped" to an 8x10 aspect ratio and now crop it with an 8x10 ratio, will the 8x10 print from Flickr look the way it does on the screen, or will it still do some sort of cropping that is impossible to predict? [and if it IS already cropped to an 8x10 ratio is there anything else I can do to get the print to look the way it does on screen?]

Finally is there some setting in the camera I ought to be using to get the best prints with "best" prints being those that fit standard prints of 8x10, 5x7 or 4x6? If not is there a standard sized print that works best for this camera with "best" meaning a print that matches what shows up on my screen?

I dont know Flickr well enough yet to know how their printing works, but any professional enough printing service should have a manual cropping tool. You should be able to set the crop, and then order the print. If they dont allow you to do that, then picking a non 3:2 aspect ratio print is like a crapshoot. Dont order anything but 3:2 then, or find a different printing service, or upload image as a 8x10 and print.

Your camera will always output 4x6, so anything else will need cropping or padding of somekind. Hope you get it sorted,

I'm not quite understanding why you don't upload an image cropped to the aspect ratio that you would like printed.