correct way to cvsup ports for -stable

[Jozef Babjak]

Hi!

A similar topic has been disscused here several days ago, but I still don't
understand, how correctly update ports tree via cvsup. I have installed
4.9-release. I upgraded to -stable according to
/usr/share/examples/cvsup/stable-supfile (I have changed only '*default
host=...' line, all rest I kept untouched) and I done make world and kernel...  
I understand well how to upgrade system, but my questions about ports are:

1) Is it ok to upgrade ports, or do I have keep ports instaled from -release CD?

2) If I should upgrade ports, how exactly? Which file from examples I should use 
and how I need to modify it? There is nothing about ports upgrade in 
stable-supfile and ports-supfile deals about -current. Is it enough to use
cvs-supfile from examples directory, change a cvsup server and comment out 
'doc-all' and 'cvsroot-all', isn't it?

Sorry for (maybe) stupid questions; I read comments in stable-supfile and 
handbook, but this is still not clear for me. 

Jozef