If you edit on a calibrated monitor, and the lab does due diligence in maintaining and calibrating their printer, you can expect very good results with NO ADJUSTMENTS. I get good results from both Adobe RGB and sRGB images, but the latter is probably safer.|
If the lab is careless about calibrating, or ignores your instructions, no amount of persuasion on your part will have any effect. Change labs!
Cropping is another matter. The operator will always crop about 2mm from the edges for a borderless print, even if it is sized exactly. If it is not sized exactly, they will crop from the shortest side to make all edges borderless. It's hard to predict what they will do on bordered prints to get even borders. This is a real problem if you compose to the edges of the image - things get lopped off. The best solution is to crop the image exact size (but less than full size) and aspect ratio you need for composition, and place it inside a blank border (canvas) sized to fit their printer (e.g., 8x10 or 8x12). When they crop, only the blank edges will be affected. Give the lab an "heads up" on your strategy.