IS IT NECESSARY TO ADD ANY FILE SYSTEMS ?

Basically, no.  RDPrep, using the defaults, creates FastFileSystem
partitions on your hard disk.  The FastFileSystem is presumed to be found
in the L: directory of your Installation disk.  The "old" file system is
found in your Amiga's ROM if your ROM is a KickStart 1.2 or 1.3. In
KickStart 2.0 ROMs, the FastFileSystem is found in ROM. 

Thus, you'll only be using the features of Screen 3 if you are adding
some experimental or variant file system to the RDB area of your hard
disk.  Once you've added a new file system, you must go back to Screen 2
and designate which partitions, if any, will make use of that file
system.

FILE SYSTEM TYPES:

When you add a file system name to the list in Screen 3, RDPrep will
assign a "DOSType" designation to it consisting of a hexadecimal
representation of the ASCII name of the DOS type. See page 3-3 of your
AmigaDOS 1.3 Enhancer manual for additional information. Note that this
designation is NOT editable for the old or the Fast filesystem; only for
variant file systems you may choose to add to the list, so unless you're
using some variant file system you don't have to worry about it.

The GlobVec value should always be -1.

Priority should always be set at 10 (never higher lest you interfere with
other important system tasks). You can set it lower than 10 but your SCSI
interface response will suffer accordingly.