Gray areas in Tolkien's LotR

[jusu]

As Tolkien himself said in LotR preface, there are some gray areas in his books which he, as others had not noticed them, hadn't corrected. I wonder whether you folks have already discussed this subject but here are some issues which I have noticed (perhaps there is an answer, had I read (and listened the audio)book more carefully:
1. Did the Black Riders fear Aragorn so much at Withertop (?) that they didn't attack again and take the ring from Frodo?
2. After distroying the ring Sam woke after a fortnight of sleep? Did Aragorn but them to deep sleep to heal like they have done nowadays to some badly hurt formula drivers?
3. Theoden knew Dernhelm, as he asked him/her to ride against Haradrim but didn't recognize her as Eowyn (always wear a helmet like a good biker)? And Theoden was not surprised to see Merri there?
4. How could Faramir know Aragorn and call him king when he woke up in the Houses of Healing. Had Frodo or Sam told him when they met or perhaps Gandalf? He had not seen Aragorn before?

There are probably some more but still this magnificient book is as tight and accurate as a fantasy book can be.