For short periods of time, prescription medications (such as narcotic pain medications or muscle relaxants) may be helpful to alleviate pain or related complications.
It can take anywhere from 4-10 hrs. now if your head gasket is warped you will have to take it to have it milled that takes from 1 day to several days. if not you can just buy a completely new one that fits perfectly for about $150.
As you can imagine, it costs a lot of money to fix a head gasket leak because the mechanic is going to have to remove the head off the top of the engine, which will take a lot of labor hours. A repair like this can easily cost between $1,000 and $2,000. Another common source of a leak is the radiator.