before I pull the cylinder heads

Hi,I have a 2007 Mazda6 with V6 engine, automatic transmission, 57,000 miles, mostly on the East Coast, some corrosion on the outside of engine. Engine is using coolant at the rate of about a quart every 100 miles, you can smell burning coolant from 20 feet away.

1. Is there anything else to check before I pull the cylinder heads?
2. Is there a chance of a cracked head at the water jacket?
3. What is flat rate time for cylinder head gaskets replacement?

Is there anything else to check before I pull the cylinder heads?Is there a chance of a cracked head at the water jacket?What is flat rate time for cylinder head gaskets replacement?

Thanks!