I do alot of artist blacksmith work, I have made springs but allways had them hardened professionally,I reversed the eyes on a set of leafs recently, you can cut hard spring steel with a grinder, drilling it is quite hard but you can use a masonry drill bit if you sharpen it.
If you get the spring steel too hot it cracks when you bend it and it burns realy easly, using a forge to heat. not a gas torch