Are the holes in rims drilled to suit your make of car when you buy them or are they already make-specific?

They are already drilled by the manufacturer. There are 4 or 5 different bolt patters used throughout the industry for 4 lug and 5 lug wheels so it's best to know what pattern you need before shopping for wheels. You should know the offset too. Model specifis car forums are good places to find out anything you need to know about your car.