[cdru]

I think someone told you wrong. AFAIK, there are no coolant passages in the timing chain cover. I've never heard of any issues with that cover causing cooling problems. Are you sure they weren't talking about the lower intake manifold gasket?

Any time you loosen or remove the subframe bolts the bolts should be replaced. They are TTY bolts and are meant to stretch. Each time you use them, the stretching becomes less and less elastic.