Dave,
I'll answer the simple question first: the cheese is, as local tradition suggests, a nice and creamy but quite un-adventorous young Gouda.
Ans then, one of the important questions in life: how does one pronounce "geuze"?
Firstly, it depends on whether you are a Flemish- or French-speaking Belgian. In the former case, the initial "g" is that soft sort of one, similar to the g:s in for example Van Gogh; in the latter case, it is a standard hard "g".
The "eu" is a long dipthong sound very similar to the English "u" in "church".
Finally, the "ze" is just a longish "s".
So an approximate sort of sound transcription might be "schus" (Flemish) or "gus" (French), provided the "u" is pronounced as in "church".
As to why the wired champagne cork, it is because it is to all intents and purposes a champagne bottle, and has to be in order to handle the pressure that can build up through secondary fermentation in the bottle.
It is also one of the odder beers in the world, for a number of reasons.
For starters, the wort is made from about 65% malted barley and the rest unmalted wheat. Then, only overaged hops are used, which have the preservative qualities, but no flavour, i.e. no bitterness. Furthermore, once the wort has been cooked, no controlled yeast strain is added; instead the wort is left to cool in shallow, open tanks so that the local microorganisms can dive in and get to work, providing what's called spontaneous fermentation.
The result of this process is a beer called lambic. This can either be drunk as such (and will then be pretty much completely flat) or put into oaken vats to further ferment and mature for between one and three years.
To make geuze from the lambic, a number of different age lambics will be selected and blended ("assembled" is the usual word in the trade), and the results bottled in those champagne bottles and left to mature for at least six more months. Provided storage conditions are decent (stable temperature and humidity), there is hardly any upper end to how long a bottle of geuze can be kept. The oldest ones in my cellar are from the late 1990s, and on a couple of occasions I've drunk geuze that was bottled in 1984. There is a marked development of flavour over time, ususally with a somewhat unpleasant sulphuric phase somewhere around the five-year mark, after which it tends to just get mellower and mellower.
The bottles are traditionally served in those wicker baskets, as they've been stored lying down, with the sediments settling on the bottom of the bottle; by not dramatically changing the bottle's position when opening and serving it, the sediments mainly remain settled, and the beer can be served un-troubled.
It is a bit of an aquired taste (I've a friend from the UK who refers to it as "that rubber-band stuff" ), and although in every way a true beer, not with anything ressembling a conventional beer flavour. It is quite acidic, especially when young, often tart, in many ways reminiscent of farmhouse cider, although there are no apples or any part of a cider making process involved.
Should one be interested in trying it, first of all, beware of the commercial varieties! Often referred to in Belgium as "bottle-cap geuze" (because they dont referment in the bottle, so don't need the champers cork), these are often artifically flavoured (even sweetened), and although sort of OK-ish in their own right, if that is what one is looking for, not anyway near the real thing. Only the real stuff can be labelled "oude" (=old) geuze, so that's what to look for for starters.
Secondly, if in Belgium on a Sunday, you could do worse than to visit a pub called In de verzekering tegen de grote dorst ("The Insurance Against Great Thirst"; what's in a name, eh?!) in the small village of Eizeringen, some ten miles or so west of Brussels. They're only open on Sunday mornings, but have probably the greatest selection of lambic beers in the world, and is generally a lovely place; see **LINK**. I was once lucky enough to win three months of free drinks there, although with their limited opening hours, it took some effort to properly profit from my prize.
If you buy a bottle to take home, then let it rest lying down for at least a couple of weeks before drinking it; otherwise it'll pour troubled.
There are several good brands, but my favourites are withour a doubt Drie Fonteinen, Girardin and Boon, in that order. Cantillon are good too, but very tart, to the point of potentially scaring a beginner off the stuff for good. The Mort Subite served at the lovely Brussels pub with the same name is fine, too, but to my mind not as complex and interesting as the other ones.
As you may by now have guessed, I rather like my geuze, and have taken a bit of an interest over the years … 
There it is again: you ask a simple question, and get the ruddy encyclopedia thrown at you.
Mattias
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