If you are looking for a long range, blue water cruiser, you need to look at boats designed specifically for this assignment. Catalina would probably be fine usually, but it's when you get into extraordinary\possibly unexpected weather that you may have problems. Capsize would be the least of my worries in a larger boat. Equipment failure is more likely, including rudder, rigging, sails, electronics, seals, wave damage, etc etc.
Next: Forget basic sailing lessons - At the novice level, with your cruising intentions, first discover whether or not you like sailing. Go out with friends or a captained charter. Then launch into a full-blown year-long sailing curiculum, with on-the-water training and classroom intruction, including advanced navigation, etc. Then sail your new boat solo for a couple of years, at least once a week. Read, practice, and educate yourself thouroughly during this time. Then plan your world tour. This will be the only way to be prepared when something does go wrong, or be able to anticipate\avoid somehting going wrong, regardless of boat choice.