I like your post, Ibrîn! Good work.
You proved that Aragorn was not intending to go to Mordor initially, neither was Boromir.
Gimli indeed seemed set to stick to Frodo and the Ring - but that doesn't mean that Gandalf and Elrond were of the like mind. Dwarves were not reknown for stealth, but they had a bad reputation for their greed when it comes to jewelry
. I don't think Gimli would have been trusted to accompany the hobbits to Mordor without other Big People to keep him in line.
Gandalf indeed seemed to foresee his own end and thus made no plans beyond going to Lorien.
And I wholly agree with Morthoron and Ibrin about wizards staffs.