I generally recommend once or twice a year, even if the piano isn't played much. Changes in temperature and humidity pull strings out of tune whether you're playing it or not, so regular tunings keep it from drifting too far off.

Not a problem, but it does change things a bit. A piano that's sat untouched for a long time is usually further out of tune than strings can safely correct in one pass, so it may need a pitch raise first (basically a rougher first pass to get it close) before I can do the fine tuning. I'll let you know if that's the case once I'm in front of the piano.

Yes, I work on uprights, grands, spinets, and consoles. The rate is the same flat $150 regardless of size or type.

If I run into something beyond a minor fix, like a part that needs replacing or a bigger structural issue, I'll walk you through what I'm seeing and what it would take to address it before doing any additional work. You won't be surprised by anything after the fact.