Single handing a 30-ft Catalina should not be difficult if you’re set up for it as folks have said. Ultimately, it may depend on what kind of sailing you will do as to how “successful” you are at it. But, I imagine that you have single-handed the Cat-22 so know the basics such as hoisting & reefing the mainsail and tacking and trimming the headsail, w/o benefit of an autopilot (when self-tailing winches are very helpful). On the survey question, I’d get one now b/c it’s likely now or later in any event. For boats more than 20 yr old many insurance companies require it. Some marinas require a recent one for boats over 20 yr old b/f giving you a slip. Then, there is the benefit of knowing more about what you will be buying, etc.