Very Beginning CVSup Questions

[J.C.]

I'm a beginner with FreeBSD and somewhat intermediate with Unix-like
operating systems in general, so please bear the nature of my
questions. I have some questions about CVSup that seem unclear from
the handbook. Right now I'm sticking with RELENG_7_0; I intend to
track -STABLE once I get the hang of CVSup, make buildworld, etc.

I understand that the supfile contains the list of *default settings
(*default tag=RELENG_7_0 etc.) followed by the list of "collections".
The "Using CVSup" page suggests simply using the src-all collection. I
understand that when tracking -STABLE I want to update the ports
collection before running make buildworld; is the ports collection
included in the "base source tree" (i.e. does src-all imply ports-all)
or should ports-all be included as a separate line beneath src-all?

The "Using the Ports Collection" page in the handbook says to make
sure /usr/ports is empty before running csup because otherwise "csup
will not prune removed patch files." Isn't this what the "delete" in
the supfile (as in the line *default release=cvs delete use-rel-suffix
compress) is for? Do I have to clean /usr/ports every time I run csup
or just the first time?

If I don't care about encrypted transmission or HTTP vs. CVS
protocols, are there any compelling reasons to use portsnap instead of
CVSup/csup?

Thank you very much for your help.

- Jonathan