You can find a brief confirmation of the facts
concerning Twain's having the first telephone
in Paine's biography (vol. ii, p.726, paperback,
Chelsea House, New York, 1980).  It describes
an ill-timed opportunity to invest in Bell's device.
Perhaps I should say the "facts according to Mark."

As for his consternation with the use of it, I've
read that also;  I don't have a source handy, but
will check.

It always struck me as funny that if Twain did
indeed have the first telphone in a private residence
in Hartford, whom would he have called?  The Telephone
Company?  Reminiscent of Twain's maxim about
getting the full value out of joy -- must have someone
to share it with.