Here is a break-down of knabe serial numbers:
http://www.pianoworld.com/knabe.htm
(just cut and paste the link)
Knabe was a highly respected brand in pianos. If - and I say IF - it is in very good physical and mechanical condition, it might be worth a pretty penny. But it will cost you a few bucks to find out for sure (professional appraiser is the only way to go). Good luck with it.
Nothing that old won't need rebuilding. So you have to define "good"
About $1,500 if it's in good condition
I would recommend a value of approximately $200-$400.
the piano sang beautifully when i played the piano
Willis & Co. was founded in Montreal in 1884. They made very good pianos at first, "cut corner" pianos near the end, and went out of business in 1978. I do know how you'd trace the serial number, but four digits implies an early one, if it's a serial number at all. It's likely that four digit number is not the serial number, but something else.
Any Kawai piano is a good piano (more likely a great piano) - the company makes only precision instruments.
A good website to learn piano on is go on Google and type "PIANO". Click on the result that says VIRTUAL KEYBOARD - PIANO
No, nothing can compare to a grand piano.
A Wurlitzer piano is indeed an expensive one. However, the serial number 598117 was made in Germany during World War 2 and was produced in such rareity that this one is worth at least 2,000,000,000 yen. NO JOKE!!!
A "piano virtuoso" is the correct term.
playing it, learning it, teaching people it. Playing the piano is proven to be good for one's brain.