Language issues

We've lived here in the States for more than six years now. Six years!  I'd say we've pretty much adapted to the lifestyle (although I still don't feel the need to put on Lycra just to go for a walk round the block, and I still feel daunted by ice-cream servings as big as my head). 

Linguistically we manage OK, too - especially now that our Boy can speak authentic American English for us when necessary.  I love lots of things about America English, like the cheery elision of words (Coulda, shoulda, woulda?  You betcha!).  But I'm stuck on just a few vocabulary items:

• The hair over my forehead, which I know as a "fringe", is here called my "bangs".  What's that about?
• Why the silent "h" in "herbal"?  American English is usually so good at saying a word how it looks ("Green-wich"), or spelling it how it sounds ("color", "thruway").  So why the French affectation with "herbal"?  And while we're on the subject of silent letters...
• McDonald's "Filet-o-fish" (with silent "t"). What language even is that?