Interesting stuff!
Andrath - is it known to be/have been an actual settlement rather than some sort of location/geographical feature?
I always had the vague impression that it was the name of the defile or pass between the Barrow Downs and South Downs (from UT), but would be delighted to be proved wrong!
As to the name; 'rath' is path, way or road, right? Like Rath Dinen. What does the 'And' mean (or the 'Am' in the alternative Amrath)? The Greek andros to make 'man-path' or 'Men's Road' would fit nicely I think but not sure JRRT used much Greek.
Meanwhile on Mewlips - they seem to me to be Marsh-dwellers from the illustrations and talk of bogs in the poem, so Midgewater is my suspect Mewlip-den. Though conceivably Swanfleet or even the Gladden Fields? If so, are the Mewlips really Hobbit folk-memories of Gollum??
Somewhere after leaving Bree Aragorn mentions 'spies' more formidable than Bill Ferny and that the beasts and bird can't be trusted iirc.
'Freeze his heart' might well be metaphorical. For example a band of raiding goblins, trolls or even brigands could happily commit such atrocities upon the peaceful folk of Bree such that Butterbur's heart would be 'frozen' by their (non-supernatural) savagery. What think ye?
I do like the spotting of 'dark things in the woods' - could be an owl or a deer or a wolf or.... a....a...who knows?
Maybe Aragorn & co. have the authority to prevent the wights wandering from the Downs, in the same way that A has authority to use the Palantir, due to the Dunedain nature of the barrows at least (OK a whole different kettle of fissssshhh !). The dark shapes being wights or allied spirits transgressing the 'bounds' put about their land in the absence of the Rangers. (He says, shamelessly making stuff up
).