rebuild DragonFly using gcc 4.1

[arnuld]

i wanted to have GCC 4.x based DragonFly system (for a C++ project)
and "Trevor Kendall" advised this:
------------
If you are using 1.8.x:
In /etc/make.conf uncomment WANT_GCC41=yes and rebuild.
If you are using HEAD, it is built automatically already.

To use it set CCVER to gcc41.
--------------
but "Matt" said "please do NOT use HEAD". so i used "LATEST preview
release" which was GCC 3.4 based. In "/etc/mk.conf" i added a line
"WANT_GCC41=yes" but i do not know how to rebuild ? i  tried Google
and got this:
# make buildworld
# make buildkernel
when i try this i get this message: "do not know how to build world".
funny message, i thought.  so i have these questions:
1.) Is it a good idea to use  DragonFly preview release as my
general-purpose OS. actually, i want learn UNIX and i want GCC 4.x to
work on a C++ project. i just use a Window Manager, xine-ui, firefox,
emacs, bash, gimp, audacious or xmms and nothing else. i don't use
Desktops.
2.) how to rebuild the preview release for gcc4.x and how long this
process will be ?
3.) is it necessary to do this before rebuilding world:

cvs -d anoncvs at anoncvs.us.netbsd.org:/cvsroot co pkgsrc

even after 4 hours, it is still downloading packages :-(. is it
downloading the source code of every package ?
4.) DragonFlyBSd guide also advises to use "cvs up" after step 3. what
is it and how much time will that take ?
5.) can you please provide a list of commands for rebuilding with GCC
4.1  as i re-partitioned my disk and reinstalled Arch  GNU OS (a.k.a
Linux) just to send this email. this i the only machine i have, my
home PC.
thanks in advance :-)

--
http://arnuld.blogspot.com/