The shutoffs can be anywhere in an exposed and accessible location such as a basement or inside a vanity and are nice to have but not absolutely required. You may have to move the water pipes over in the wall to be hidden by the pedistal which involves cutting into the wall. You can't have any flex hoses behind a wall so walls must be plumbed with solid pipe.
You can cut the drain pipe yourself if you know anything about cutting pipe and reconnecting traps and all of which depends upon what type of pipe you have.
Look at the pedestal sink instructions. They will specify the pipe rough in locations. If your present pipes aren't at the right height and width apart to be covered by the particular brand of pedestal you have, then you are looking at tearing into the wall to get them placed right. Water pipes plumbed into vanitys may be spread too wide and the drain pipe height with vanities may not be right. A stud location in the wall could affect the placement also. Of course, planning on the plumbing rough in locations should have been done before you started your remodel and sometimes you have to buy everything before hand to get it right. Post back when you have any more specific questions. Good luck.