I have done som (alot) of work with printer, controllers and drivers. I dont realy understand the question but there is no general tools/librarys to create a file ore chunk of data that can be sent to any printer.
In the past they accepted asci but to day most of them use some kind of coding and compression of the data that is going to be printed. The data is also in general post processed in some whay in the PC (GDI printer)One general standard still used in more expensive printers is postscript, thats an open standard and you can create printable files and send to the printer.
Re: USB printer drivers i would recomend that u use some of the tolls out there to generate drivers, its a pain to write low level USB drivers with enumeration and all that. Check jungo and windriver (search the net) the are both great tools to build a driver source for windows.
If u be a litle more specific in the question I might be able to give a better answer...
re Me