Tuning is the main issue, and the advice you've read is good. Once each year is a minimum; twice is better. More often for a piano receiving particularly heavy use. My pianos are used a few hours each day, and twice a year is fine.
The "overhaul" you're reading about is likely "regulation." That's a process by which a technician goes ...
That screw is known as the "let-off regulating screw" (see part #28 in the linked diagram). Yours appears to be a "spade screw" (below). To adjust it, you need a "Piano let-off regulating screwdriver" like the one shown below.