If your PBP directory look for 18F2550.INC. In this file you'll see something like
LIST p = 18F2550, r = dec, w = -311, w = -230, f = inhx32
INCLUDE "P18F2550.INC" ; MPASM Header

If you don't have the w = -230, then just edit the file and save it. That
should take care of the 230 warnings.

_ICPRT_OFF_4L is not a valid fuse option for the 18F2550. If this is in your
18F2550.INC file just delete it. For a list of valid config fuse options, look
in the P18F2550.INC file in your MPLAB installation directory, or look in the
Special Features section of the data sheet.

This is only available on 18F4455/4550 devices in 44-pin TQFP packages.

For the "Cannot open file" errors, place these files all in the same directory
where the .bas file you're compiling is located.

I create a USB project directory specific for each different USB project, then
place all support files in this directory.

HTH