Outofwhack- With the metals blades there should be no reason they should not go to time life, 5000hrs I beleive, However, you may want to look round for another set soon if you intend to keep the machine, they are pretty scarce to come by. The cracks you mention,once you have them check are usually OK from leading edge to trailing edge. The ones you don't want run along the blade. You sometimes find the cracks around the root end near the metal brace, close to the grip. Normally the paint on the surface cracks, that's my expirence with woodn blades too, as you say probably due to coing, not all down to Auto's either. I know a couple of places that may help you. Rotorcraft Blades in Texas, and East Coast Helicopters in PA.
All the best
Darren