I can answer a few of your questions. As to whether the repair is worth it, only you can decide that, on the cheap and you doing the labor, it may be possible to repair the head and renew the gasket for about $500-600, dollars.
You don't say how many miles are on the engine, does it use any oil? Is there a need for any repairs while you have it apart? Timing belt pulleys and new valve seals? A new engine could make sense and maybe even easier to swap out.

Yes, the head can warp, and/or be cracked, and you will need a new head gasket at the least, also get the head repaired, other wise the new gasket will fail fairly soon.

It is an involved job to do, special tools would make it simpler and quicker.
But these tools are for dealers who are against a clock on repairs and who will be doing many jobs for the cost of the tools. It can be done without them. There are just some work arounds to perform.

DanR '94 964 343,000 miles (109,000 on the new engine)
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DanR