Nice boat! And welcome.
My First 260 has the exact same mechanism, just larger.
You can sail with it partly (or fully) up if you want. The sail trim balance will be effected, and you will not point as well, but you can do this if you want to clear a shallow area.
I don't know how many turns to gain 1 foot of draft reduction.
Use a good grade marine grease on the screw. Unwind it while the boat is on the trailer and put grease sparingly on the threads. Screwing it back in will spread it around. Go up and down several times, and look for missed spots. Too much makes a big mess.
A hard spot while turning sounds like a burr on the screw. It would get hard when it hits the nut built into the top of the outer tube. If will probably de-burr over time. A PDF of the engineering drawing of the screw is on my blog here.
https://rarerarebird.blogspot.com/p/260-documents.html
