All that stuff depends are the image itself. Depends on what your outputing to,as well. When I print to the Durst Lambda. The res. for the Lambda is 200/400 ppi. You can even go low as 150 ppi.
I did a retouch on an 11 x 14 org. print. The person wanted to output to 16 x 20. So it was scanned at 400. I should say it was scanned for output 16 x 20 size......400 dpi res. from the scanner(flatbed). I did the retouching on it.......Leaving it at that size and dpi. For output to the Lambda. Inkjets and cmyk printing are different. Wasn't bad. For a scanned 11 x 14 print from 1969.