Weird stuff we say in Church

In Church today, not for the first time, I was struck by the seriously strange things we say as Mormons that we never actually think about.  One of my favorites is: "The Book of Mormon is true."  What do we mean by that?  We never say it about any other books.  We don't say "I believe that Hawking's A Brief History of Time or Newton's Principia are true."  We don't say that about Hamlet, or Great Expectations or Huck Finn.  What exactly do we mean? Even stranger is "The Church is true."  I'm not against saying that--I just don't know what it means, except a sort of generic 'yay, rah, us!'
I'm dumb that way.  In church today, we heard a talk about the afterlife, and someone mentioned 'Spirit Prison."  What's Spirit Prison?  It suggests that spirits can be, in some sense, restrained, that there are cells to put them in, or shackles to fasten them with.  Doesn't really fit my understanding of what 'spirits' can do. Seems they'd just float on out of that prison. Then I thought about haunted houses, where ghosts of people killed in some horrific way can't leave the place where the horrificness happened.  Bingo!  Spirit Prison!  Then it made sense to me.  
It's a curse, really, to hear some absolutely commonplace Mormon phrase and drive myself crazy trying to figure it out.  "Stakes" for example.  I get the tent metaphor, but if the main tent is in Missouri, and there are a million stakes holding it up on its west side, and twenty on its east side, that seems to me a seriously lopsided tent.  And, think about it, the name for one of our major organizational units is a tent peg?
We also have all these names we use for youth organizations.  I adore 'Sunbeams.'  It just fits, their cute little smiles, their amazing running noses, those darling twenty minute tantrums. I love the Primary program, with the boys sucking on their clip-on ties, the girls with bows in their hair and band-aids on their knees.  As I left Church today, I saw three little kids sitting waiting for the next meeting.  One little boy had his suitcoat and tie, holding his basketball, another little boy was wearing seriously awesome looking shades.  And a little girl was beating her Barbie's head in against the pew sides.  Sunbeams all.
But Beehives?  We named one of the age groups in our youth organization after 50's hairstyles?  Mia Maids sounds like they're hanging out with Robin Hood's Merrie Men.  And Laurels reminds me of that mean-girl-black-comedy, Heathers.  Like, if you're not named Laurel, you're not cool enough to hang with us. 
We used to have two organizations for older single people: M-Men and Gleaners.  M-Men made it sound like guys couldn't get married because of their stutter.  And Gleaners, isn't that a lovely metaphor.  Like, all the good guys have already been harvested, so your job is to glean.  "Good enough for the dregs" should be their motto. 
I don't get why we use 'thee' and 'thou' when we pray and never any other time, and I don't get why we pray for 'moisture' instead of 'rain,' and I don't get why we insist on 'nourishing and strengthening' our bodies.  Seems to me that if they're nourished, they'll also get stronger. 
I also don't get why we'd want to 'hie' to Kolob.  But that's another conversation altogether.