>1)  When Twain so famously swore, what exactly did he say?  What kind
>of swearing did people do in the 19C?

I trust you've explained to your students that DESCRIBING swearing rather
than quoting it was a  common Victorian literary convention, and one that
Twain handled beautifully (e.g., in "Jim Baker's Bluejay Yarn")  We're
always being told in Victorian books that sailors swore splendidly, etc.

While  some matters of syntax might have evolved,  the basic swear words
certainly have not changed.  Nor were they new in Shakespeare's day.  Young
folk (maybe most folks) seem often to have a vague notion that dirty words
are new.  When the topic arose in  my classes, I would suggest that just
possibly  human bodily functions  were a trifle older than computers.

Twain's "1601" offers ample evidence that he knew all the basic words, and
a good many others.  Because  the sketch is set in Tudor England, of
course  the turns of phrase are intentionally archaic.  Perhaps it is most
modern when Twain has Queen Elizabeth say "Oh, shit!"

In a letter to Howells, SLC creates an imaginary situation in which Howells
purportedly calls someone "a quadrilateral, astronomical, incandescent son
of a bitch" ....though we can hardly suppose those delicious adjectives
were meant to be everyday profanity.  I recall a letter  to his brother
Orion where SLC bursts out with "Jesus Christ!" exactly as someone would
sayit now. Prhaps other people will come up with other instances.

This is tangential to your question:  He buries a few obscenities, shady
jokes and such in his writings meant for publication, but my hunch is that
there's less buried bawdy in Twain than in, say, Melville.

I'm thinking of the half-veiled sexuality in the camp meeting episode and
some of the other Duke & King scenes in Huckleberry Finn.  Or the business
in A Connecticut Yankee where we're told that  a nunnery sits on a hill
opposite a monastery.  (I'm paraphrasing from aging memory:)  "And these
were friendly unto those, and in the valley betwixt they did erect a great
foundling asylum."   It seems to me mostly very tame stuff, and well hidden.

Mark Coburn