Sorry really busy period so I'm going to have to take these questions one at a time. First of all the question about the article...
This is an interesting one, because it seems to me it links to what we said
here about the optional omission of the article when talking about people's roles - eg
Barack Obama is (the) President of the United States
In both cases (ie your example and the one above) the use of the article is optional and in both cases we're talking about the
function of the person/thing. Some more examples :
Mr John Roberts, a Panama expert who
served as general counsel on the Senate Armed Services Committee
...The Qing dynasty that
served as example for the Nguyen emperors
...the shaman , who
functioned as priest, soothsayer and healer
Until 844, Alcácer
functioned as center for the collection of taxes in the lower Sado valley
...and is
used as prop controller for the bottom hatch and wench of the Firefly-clash ship 'Serenity'.
However, although plenty of examples without the article exist, it does seem to be much more usual to include it when things are involved. It's much more common to omit it when people are involved.