There are hints that he served in Rohan1
On the road to Helm's Deep while having dinner with Éowyn, she mentions something Théoden had told her:
My uncle told me a strange thing. He
said that you rode to war with Thengel,
my grandfather. But he must be mistaken.
King Théoden has a good memory. He was
only a small child at the time.
Short answer: They walked home, unclad.
The last thing Frodo sees at the ford is
At that moment there came a roaring and a rushing: a noise of loud waters rolling many stones. Dimly Frodo saw the river below him rise, and down along its course there came a plumed cavalry of waves. White flames seemed to Frodo to flicker on their crests and he half fancied ...
From Unfinished Tales it is said that the palantír could only see as they did not transmit sound.
Alone the palantír could only ‘see’: they did not transmit sound.
By themselves the Stones could only see: scenes or figures in distant places, or in the past. These were without explanation; and at any rate for men of later days it was difficult to direct what ...
It's only hinted at, but I think yes.
In addition to Edlothiad's answer, Aragorn tells Boromir he's seen Minas Tirith "long ago."
Boromir: I will find no rest here. I heard her voice inside my head. She spoke of my father and the fall of Gondor. She said to me “Even now there is hope left.” But I cannot see it. It is long since we had any hope. My ...
The Nine returned to their master and drew strength again, before being sent out on their new winged reptilian mounts. They stay hidden on the eastern side of the Anduin for several months, until after the Breaking of the Fellowship on February 26, 3019.
‘Nazgûl, Nazgûl,’ said Grishnákh, shivering and licking his lips, as if the word had a foul taste that ...
TL;DR – It’s not so much that Boromir is “un-Numenorean” compared to Denethor/Faramir, it’s more that Faramir, like Denethor, is a throwback to the Númenóreans from before the Akallabêth.
Boromir, is more representative of other Gondorian lords of their time
The sons of Denethor II, Boromir and Faramir, are descended through their father from the Steward of ...
Regarding "sea longing":
As noted in another answer, the "sea longing" is actually a longing for Valinor, which simply put is "paradise". When elves first appeared in Middle-Earth, they were invited by Valar ("the gods") to come live with them in Valinor.
Those elves who accepted and started the journey to Valinor are ...
Fritz Leiber seemed to think so, and he asserted that the sentiment was commonplace (even if not everyone would admit to it):*
There’s no arguing that a vast number of people—intelligent, educated, and sensitive people, I mean—young and old (but especially the former) — are tremendously and enduringly enthusiastic about Tolkien’s trilogy, yet I do meet ...