F.A.R. 65 was indeed a Wurttemburg artillery regiment. Whether or not the markings are original or not, I can't tell from the photos. It looks like the felt helmet body has some serious staining issues to it. Maybe that is why the photos are dark, in order to hide the staining.
The Prussian 87th Infantry regiment helmet has certainly seen better days, which is sad. Serious dry rot issues with an incomplete leather sweatband, and some serious flaking to the finish on the helmet shell exterior. I'm not good enough to say whether the frontplate banner is real or not without seeing the backside of the frontplate. Others members can probably say for sure whether or not it is real, if they see this posting.
The ersatz 74th/77th/78th infantry regiment helmet has an unusually long screw/bolt coming through the rear visor, with no nut on the screw. Might that have been repaired?
Hessian brass enlisted frontplate looks o.k. It also has residue of old cleaner left on it, from someone polishing it up in the past. Looks like it's getting a patina back on it again, which is good to see.
e.m. infantry chinscale set looks real. Heavily cleaned, however, and has loose scales that may or may not have been repaired.
Just my observations, for whatever they are worth.
All the Best,
Alan