First, and most important, you really should log onto the Catalina 25 National Association, where you can tap into the knowledge and hands-on experience of hundreds of sailors who have sailed and repaired C25s for as much as 35 years. It's a tremendous resource for you. Here's the link. Association Forum
You need the four pilings of course. Also, you need a way to board the boat, and that's probably the "walkway." That term isn't used in my area, but I assume it's a finger pier that extends from the dock to each of the pilings.
When you leave the boat unattended for 5 months, you really should hoist it out of the water and store it onshore. In a hurricane, storm surge can raise the water level 5-6 feet, or more, and this photo shows what can happen to a C25, or any other boat. The water level must have been raised 7-8 feet to leave the boat on top of those pilings. A boat lift won't help that.
A boat lift will make your antifouling paint last longer, and keep your bottom cleaner, but if you haul the boat once a year, that will give you an opportunity to roll on a single coat of ablative antifouling paint. For your boat, it should only be a 2-3 hour job. (30 minutes to wash the dirt off the bottom, 30 minutes to apply masking tape to the waterline stripe, and 1-1/2 hour to roll on the paint.) One coat of paint will easily protect your boat for the 6 months that it is in the water. A boat lift is nice in some ways, but I really don't see enough value to you to justify it's cost, not to mention the fact that it's something else to maintain and repair.