[Tuor in Gondolin]

I've always viewed the sender of the dreams to be Eru.
By then it was pretty clear that the Valar plan of sending
the Istari was insufficient, and to some extent counterproductive,
and I believe (in Letters?) it's said that gandalf was sent
back enhanced because the original Vala plan hadn't worked.
Since Faramir got most of the dreams it seems he was meant to
go, and while Boromir would probably have not let frodo go on,
if Faramir had been in the Fellowship it's less likely he would have
been tempted, and might even have gone with frodo at leats through
Ithilien.