Rebuilding, Got Questions

[beno]

Hi;
The box I've taken over has BSD 5.3 so I need to upgrade. This is a big 
jump and the console is half a world away so I have some questions:
* Can I do all of the steps of the installation without reverting to 
single user mode?
* Where do I find the src to download?? All I find are ISOs. Is there no 
*.tgz file anywhere?
* I'm upgrading from 5.3 to 6.1. Will I have to run "mergemaster -p" 
before running "buildworld"?

Do I need anything more in /etc/make.conf than the following?
CFLAGS= -O -pipe
NO_BLUETOOTH=  true    # I have no need of this
NO_SENDMAIL=   true    # I use qmail

The current /etc/make.conf has this and I don't understand why:

# -- use.perl generated deltas -- #
# Created: Wed Dec 21 21:11:27 2005
# Setting to use base perl from ports:
PERL_VER=5.8.5
PERL_VERSION=5.8.5
PERL_ARCH=mach
NOPERL=yo
NO_PERL=yo
NO_PERL_WRAPPER=yo

Should I leave the above? Merge the two? Throw out the above and just 
use what I've written (above that)? Will that screw up the installation? 
Will that screw up perl?

Here is my procedure. Look good?

cd /usr/src
make -j4 buildworld // single CPU system
make buildkernel
make installkernel
reboot
make installworld
mergemaster -p
reboot

TIA,
beno