"high speed" is a relative term... to some that may mean 10ppm, while for others it may be more than 40ppm.
as for scanning to a PDF, that's a software function. even if the scanner software doesn't do it directly, tiff-to-pdf converters can do the job. google "tiff to pdf".
Can you recommend a High-speed scanner that will work on a network. If it has a printer, fax and make the scanned doc a PDF much better.