Scan straight into Gimp is file -> Create -> Scanner
Gimp 2.8.x is 24 bit (8 bit x 3 channel) maximum, so even if your scanner produces 48 bit (16 bit x 3 channel) you will only get 24 bit.
This is an ancient Canon LIDE30 scanner in Windows, typical sort of interface, scans directly into Gimp using the Canon TWAIN driver: screenshot http://i.imgur.com/ivG9AsW.jpg
My more usual linux setup, and while this is Gimp 2.9.5 which will handle 48 bit (16 x 3) the scanner driver (SANE) cannot handle that resolution. Still get 24 bit: screenshot http://i.imgur.com/Q4fsBE5.jpg
All you can do is try and see what you get.
Probably scan to a 48 bit tiff and open in Gimp 2.9.5 is your best bet.
For Windows there is a Gimp 2.9.5 at http://www.partha.com
For the rest of your question - data transfer, it will be some type of lossless format, SANE for example, while you can specify a format, defaults to pnm. As important is the ppi used for scanning, 300 for photo quality, increasing the ppi above about 600 is usually a waste of time.
Gimp 2.8.x is 24 bit (8 bit x 3 channel) maximum, so even if your scanner produces 48 bit (16 bit x 3 channel) you will only get 24 bit.
This is an ancient Canon LIDE30 scanner in Windows, typical sort of interface, scans directly into Gimp using the Canon TWAIN driver: screenshot http://i.imgur.com/ivG9AsW.jpg
My more usual linux setup, and while this is Gimp 2.9.5 which will handle 48 bit (16 x 3) the scanner driver (SANE) cannot handle that resolution. Still get 24 bit: screenshot http://i.imgur.com/Q4fsBE5.jpg
All you can do is try and see what you get.
Probably scan to a 48 bit tiff and open in Gimp 2.9.5 is your best bet.
For Windows there is a Gimp 2.9.5 at http://www.partha.com
For the rest of your question - data transfer, it will be some type of lossless format, SANE for example, while you can specify a format, defaults to pnm. As important is the ppi used for scanning, 300 for photo quality, increasing the ppi above about 600 is usually a waste of time.