Sven,
The photo with the possible road near the cliff hole tee is the third to last one you posted above. Either a road or a path (in those days there wasn't much difference) runs from behind the tee and off the left side of the photo.
I don't know who Piscator ("fisherman") was. The pen names golf magazines seem to have been very fluid.
It is just a hunch on my part but when I read these various articles about Biarritz I get the sense that many of them were written by the same pen. A similarity of description, repeat similar references, etc. As for the gap in Hutchinson's visits, it is again probably more of a hunch on my part related to the fact that the author of the 1908 article (who I assume is Hutchinson, but I may be mistaken) mentions he hasn't been there in 14 years. At one point a few years ago, I went through competition listings in Golf for Biarritz trying to track Hutchinson's visits, and I think he only shows up for that first season. I'd have to take another look at the real magazines to verify though.
I could easily be wrong about all this, though, but even if I am I still don't get a strong sense of confidence in the possible routing in the Chambre for early 1906, possibly outside of the hole down (9) and the hole out (14.) And I don't have sense of where the tee for the Cliff was, and that seems important in determining the locations of the other four holes ( probably 10-13.)
Note that in the 1908 article, one photo calls the hole down the 8th tee but in another photo calls it the 9th (and the green is called the 9th.) The text refers to the hole down as the 8th hole, and the Cliff hole as the 13th. And the article says there are five holes in the chambre. Note also that the 1909 article identifies the hole along the wall of the Chambre as the 13th tee, but the caption says it is the tee for the cliff hole.
[Thanks for linking to that french website. I had gotten much of my information off that site a few years ago, but thought it was in NLE.]