Slow down and breath... The kinds of questions that you are asking are by at too fine a focus. Start reading more broadly about long distance cruising and routing and quickly you will learn that it costs way more than a $1000.00 to cross through the Panama Canal these days when you add everything up, but that is also way cheaper than prepping a boat and sailing around Cape Horn even if you can cut through the Straits of Magellan.
There is a lot more to your question "What sort of strucutal damage does a boat take from prolonged exposure to rough seas?" than can be answered here. But in a general sense, a coastal cruiser with heavy use might sail a 1000 miles a year in mostly moderate conditions. A boat sailing around the Horn will sail 10,000-15,000 between ports of departure and where it would cross a path out of Panama, and so experiences the equivilent of 10 to 15 years of hard use. Its not just the rough seas that do in a distance cruiser but the relentless continual motion. The Duldrums can do a more damage as a three day low pressure system.
Hunters, Catalinas, and Islanders are all coastal cruisers. While with luck and skill and courage you might sail one long distances, for all kinds of reasons beyond standing up to the abuse of long term voyaging, they are less than ideal choices.
I would suggest that you take this a step at a time, study and read the usual sources, and then come back as you develop more orderly questions.
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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay and part-time purveyor of marine supplies