Before you jack up the car, and if its had WD-40 applied to it, apply the tyre lever to the nuts, and let it hold in place.
Then kick it in the appropriate direction. Sometimes the sudden force is enough - then once its twisted a half turn, move to the next. Once all are loose, then jack the car up and attempt to remove them in the normal fashion.
Is the tyre off the ground? If so, try kicking the tyre and see if the force of kicking the tyre is enough to rock the tyre on the bolts, it has possibly rusted to the axel - not good however.
If all else fails you have two options.
1 - You have roadside care - call them. (If your asking here however, and waiting this long, I don't think this may be the case)
2 - Call the nearest tyre place for support.
As for tightening the nuts, and crossing the wheel, it provides equal stresses upon the wheel, and ensures it fits correctly.
I run into the same thing in IT, if you start on top left when mounting a piece of equipment, you then go bottom right, bottom left, top right - its more likely to line up with all the correct holes.