I don't think there is a default value as pkgsrc is semi-independent of NetBSD
and used on several OSes & platforms.
You can browser the pkgs by catagory here:
ftp://ftp.NetBSD.org/pub/pkgsrc/current/pkgsrc/README.html
Each pkg page has a list of binary versions available; you can download those and
install them if appropriate, or do it all in one step so to speak:
ex. install 2012-Q2 binary of gtar pkg for MirBSD on i386 platform:
% sudo pkg_add -f
ftp://ftp.NetBSD.org/pub/pkgsrc/packages/MirBSD/i386/10uB0_2012Q2/archivers/gtar-1.26.tgz
As to your PKG_PATH question, according to PKG_INSTALL.CONF(5) you should be able
to display the current value using 'pkg_admin config-var PKG_PATH'. When I run
that I don't see anything, and, since I've not set it in my shell session I assume
there is no default value. If you install the pkgin pkg it might set it for you.
The pkgsrc documentation has specifics on how to set it manually:
ftp://ftp.NetBSD.org/pub/pkgsrc/current/pkgsrc/doc/pkgsrc.html#using-pkg
From what you've posted I'd guess you could set PKG_PATH like so:
% sudo -s ## become root
# export PKG_PATH='
ftp://ftp.NetBSD.org/pub/pkgsrc/packages/NetBSD/i386/6.0/All'
To test, install the p7zip archiver:
# pkg_add -v p7zip
pkg_add: Warning: package `p7zip-9.20.1' was built for a platform:
pkg_add: NetBSD/i386 6.0 (pkg) vs. NetBSD/i386 6.99.16 (this host)
bin/7z
bin/7za
man/man1/7z.1
man/man1/7za.1
man/man1/7zr.1
share/doc/p7zip/README
share/doc/p7zip/commands/add.htm
...snip...
Package p7zip-9.20.1 registered in /var/db/pkg/p7zip-9.20.1
Hey, it works - Yay!