Frodo overhears the Gaffer say to the Black Rider, "No, I can't give no message."
What would the message be?

Round the corner came a black horse, no hobbit-pony but a full-sized horse; and on it sat a large man, who seemed to crouch in the saddle, wrapped in a great black cloak and hood, so that only his boots in the high stirrups showed below; his face was shadowed and invisible.
When it reached the tree and was level with Frodo the horse stopped. The riding figure sat quite still with its head bowed, as if listening. From inside the hood came a noise as of someone sniffing to catch an elusive scent; the head turned from side to side of the road.
A sudden unreasoning fear of discovery laid hold of Frodo, and he thought of his Ring. He hardly dared to breathe, and yet the desire to get it out of his pocket became so strong that he began slowly to move his hand. He felt that he had only to slip it on, and then he would be safe. The advice of Gandalf seemed absurd. Bilbo had used the Ring. ‘And I am still in the Shire,’ he thought, as his hand touched the chain on which it hung. At that moment the rider sat up, and shook the reins. The horse stepped forward, walking slowly at first, and then breaking into a quick trot.

‘All right, cousin Frodo! You can keep your secret for the present, if you want to be mysterious. In the meanwhile what are we to do? I should like a bite and a sup, but somehow I think we had better move on from here. Your talk of sniffing riders with invisible noses has unsettled me.’ [emphasis added]

Pippin and Sam had remained flat in the grass, and had seen nothing; so Frodo described the rider and his strange behaviour.

In the previous chapter, we are given the impression that Sam will get to "see Elves" (a phrase used twice by Sam and once by Gandalf) -- so where else could Frodo be going but Rivendell? Why the uncertainty here?

Even before Gandalf has that unexplained foreboding of danger, he tells Frodo that the journey to Rivendell "should not prove too perilous, though the Road is less easy than it was, and it will grow worse as the year fails." What does he mean?

Who is the reader supposed to think the Gaffer is talking to, just before Frodo sets out?

Why are we given the image of Sam as dwarf-like? Is his felt-bag hat ever mentioned again?

Is there another problem with the Shire map? We're told that the lane to Stock and Woodhall, that the hobbits follow all day on Sep. 24, "climbed away from the main road in the Water-valley, and wound over the skirts of the Green Hills towards Woody-End, a wild corner of the Eastfarthing." But on the Shire map, that lane never intersects the main road; instead it runs from Tuckborough in the west to Stock in the east. And is it likely that Tuckborough, which looks like a sizeable town, is only serviced by this one road, would be "not much used, being hardly fit for carts"?

The fox has "seldom heard of a hobbit sleeping out of doors under a tree", and feels that three hobbits doing so is "mighty queer". But Frodo, Pippin and Sam, though stiff in the morning, seem unfazed. Is it so unusual?

Concerning the brook where the hobbits wash before breakfast on Sep. 23, we're told they go "across the stream where it dived under the road". A culvert?