Hi Amalric,
There is a question about how long the Cherusci had been speaking a germanic language. The idea that they were one of those speaking another language, along with several other groups sandwiched between the celtic and germanic speaking worlds, has been floated for many years now. It's true that the romans saw them as germanic, but the language change may have occurred only a century or two before the time of Arminius. However, the germanic language of the 1st cent AD was probably different from the early germanic texts that we have.
There is a re-enactment web site about the Chasuri though it's in german I'm afraid. However, the gallery may be of interest to you:
http://www.chasuari.de/galerie/galerie.htm
There's also a Cherusci re-enactment group in the USA, though i don't know how authentic they are:
http://legvi.tripod.com/cherusci
their shields seem to be quite different.
Most of the clothing later, including viking, re-enactors use are based on the 3rd and 4th cent bog finds, so you won't find much difference. The following image:
http://www.chasuari.de/galerie/bilder1/bild11.htm
is more authentic as far as the shield boss is concerned, it has a point which is typical of the early germanics. The wooden idol in the background is based on an actual find from the first or second cent. AD.
There is another site
http://www.westfali.de/
which seems to have a subsections. One is about the bructeri, 1st cent AD:
http://www.westfali.de/brukterer/
Again, german only but with good pics:
http://www.westfali.de/brukterer/fotos.htm
with shields again similar to the Chasuari re-enactors:
http://www.westfali.de/brukterer/meppen2005.htm
Hope it helps you a little.
best
Harry Amphlett