I used my previous boat in lakes for a decade before venturing out to salt water. I was fearful that putting the boat in salt water for even a few weeks would corrode everything. The stainless steel fittings would rust out, the engine block would disintegrate, the electrical connections would short circuit and the flux capacitor would fail.
Yeah, salt is not good for boats. But a few weekend trips won't have much, if any effect on it. The biggest threat is to your trailer bearings, hubs and brakes. The prior advice is important - rinse them out well after every launch and retrieval. SaltAway is a good idea! If there not 100% sealed, have the bearings repacked frequently.
Flushing the engine cooling water system out with fresh water is probably a good idea but remember there are a lot of RangerTugs who spend their entire lives in salt water and don't flush the engine's cooling water system with fresh water ever! Remember too that the engine uses coolant there isn't salt water flowing through the inside of the engine.
I recommend frequent waxing of everything on the exterior of the boat - fiberglass, stainless and chrome.
If you're going to spend a lot of time in warm salt water consider bottom paint. We have our boat in fresh water for 2 months followed by a month in salt followed by two more in fresh water. The critters & plants that grow on the bottom paint in fresh water tend to come off when it's in salt water & those that grow on it in salt water come off when we put it back in fresh water. If you don't have bottom paint, be prepared to power wash and scrub even harder at the end of the season to get the below water line area clean!
Another thing to consider is using dielectric grease on your battery terminals and other major electrical connections to prevent corrosion.
Have fun out in the ocean! You'll learn a whole lot about currents, tides and such. There are a lot of great places to explore out there!