It depends on the quality and miles on your existing engine. If you have a great engine, that all it needs is a head gasket, then that's better than an old engine that you may have no idea about it's history and past repairs.
If all that is wrong is a blown head gasket and even a cracked head it is much easier and cheaper to just fix it than to replace the engine. The labor to replace the engine plus the cost of the engine would be far greater than fixing the one you now have. This is assuming the engine is not worn out already.
That depends entirely on how much you value the car.
Gasket between engine block and cylinder head
You should replace the head gasket. This repair is critical to the better performance of the vehicle, and to prevent future damage of the engine.
If you get a new engine it will have a new head gasket
Were the rings replaced at the time the head gasket was replaced? Common problem when replacing the head gasket is not fixing other engine problems which usually go hand in hand with head gasket problems.
Sure you CAN, but if you do continue to run an engine with a blown head gasket you will destroy the engine. Do not run any engine with a blown head gasket or you will be buying a new engine.
If it was removed then YES.
The head gasket is sandwiched between the head and the engine block.
No. You can have the head gasket replaced. This is unless you kept driving the car with a blown head gasket and have totally destroyed the engine.
The only real option is to have the head gasket replaced. Do not pour some kind of 'miracle' sealant into your engine, because it will seal up oil passages, and the water jacket, as well as temporarily fixing your head gasket leak. The head gasket will start to leak again after a bit, no matter what you put in the engine. Having the head gasket replaced will cost around 500 dollars, unless there are problems, like the head being warped.
You must replace the defective gasket. There is no other permanent fix.