You've asked how to find out about Christianity.  That's a really
interesting question, because there are a number of sides to it, and
it depends somewhat upon what aspects you're interested in and how
much time you want to spend.  Here are some possibilities.  Probably
you won't want them all.

The New Testament.  At some point you should read at least some of it.
It's the basis for everything else, and until you get a flavor of
Jesus' teachings and the rest, it's hard to understand what
Christianity is about.  I'd suggest (1) one of the Gospels, probably
Matthew, because he has more of Jesus' teaching, although he's not as
good an historian as Luke.  (All of the Gospel-writers are overly
credulous by modern standards, but Mat. is probably more so.)  (2)
Acts, which is the story of growth of the earliest church, (3) one of
Paul's letters, since they are so important.  Probably I Corinthians.
Make sure you use a translation that is readable.  I recommend the
Good News Bible (which is a whole Bible) or the NT part which is
published separately as Good News for Modern Man.  Howver any
contemporary translation (New Revised Standard, New International
Version, New English Bible, Revised English Bible, etc.) is OK.

The most difficult thing to do is to give you a "feel" of what it's
like to be Christian.  In some ways novels and biographies are the
best for this.  You might want to pick up one of the murder mysteries
by Andrew Greeley.  Greeley is a Catholic priest, who uses novels as a
way to show his vision of Christianity.  Another book of his that you
might find interesting is "The Bible and Us", written jointly by
Andrew Greeley and Jacob Neusner.  Neusner is a Jewish scholar.  It's
a dialog about the BIble that does a very good job of presenting
Greeley's vision of Christianity (maybe better than any single one of
his novels).  C.S. Lewis' autobiography "Surprised by Joy" is also a
good choice.  Lewis is one of the most sane and mature Christian
writers I've seen.  This book describes his progress towards
Christianity.  His personality comes through it very well.

For a vision of what Christianity is about, which is very different
from Greeley's, but which is more typical of the Protestant approach,
you might try one of Dietrich Bonhoeffer's books, preferably "Life
Together", but if you can't find it and can find "The Cost of
Discipleship", the section in the middle based on the Sermon on the
Mount would also be a good choice.  Bonhoeffer was a Lutheran pastor
during World War II in Germany.  He was one of the leaders of the
underground church, and was killed by the Nazis.  His books are good
for presenting what it means for our life to be in Christ, a very
basic concept.

Finally, for an unusual but very attractive vision of what it means to
be a Christian, see Charles Williams' novel, "Descent into Hell".
This is visionary fiction.  It's very hard to describe, as Williams'
books really define their own genre.  His vision is a world where we
can carry each other's burdens in a very literal sense.  The heart of
the book is where his protagonist participates in an exchange across
time with one of his remote ancestors.  It's a very wierd combination
of fantasy and visionary Christianity.  Lewis says that Williams
actually experienced this sort of thing.  If so, he is living on a
level that few of us even glimpse.

Christians spend a lot of time in Usenet groups talking about
doctrinal issues.  This may be misleading, since it's a lot less
important in day to day life than you'd think from reading news.  But
you might still be interested.  There are two reasonable ways to learn
about Christian theology.  One is through C. S. Lewis' books.  Lewis
gave a number of radio lectures and wrote a number of books, simply
presenting basic summaries of Christianity, and intellectural defense
of it.  He is probably the best of the current "apologists", because
of his personal and intellectual sanity.  I'd recommend "Mere
Christianity", which is an attempt to summarize the most important
aspects of what Christianity teaches.  The other way into Christian
doctrine is through church history.  Lewis sticks with very basic
ideas, but not what I'd call "technical theology".  Real theology
requires an understanding of the history that it came out of, and in
some ways a church history is a better introduction to it than a book
on theology.  One standard reference is Roland Bainton's
"Christianity", part of the American Heritage Library, though there
are other reasonable books on the subject.

You asked specifically about fundamentalism.  I don't know the
fundamentalist writers that well, but you might try Francis Shaeffer
or Billy Graham, both of whom are responsible conservative writers.
(Graham is the only one of the TV evangelists that I trust.)  In some
ways this is the easiest of the areas to deal with, since all you have
to do is find your local "Christian bookstore".  They are almost all
fundamentalist.

If you just want to read one or two things, I think I'd recommend
Greeley and Neusner's "The Bible and Us" and Bonheoffer's "Life
Together".  It's hard to collapse it down to just one because
Catholics and Protestants have very different visions of what it means
to be a Christian.  Lewis tries to present "generic Christianity" in
"Mere Christianity", but there's a price to doing this (which he
admits).  Greeley's vision is of all of life as a sacramental symbol
for God.  Bonhoeffer's is of emptying ourselves and letting Christ
shine through us.  These are the two basic Christian approaches which
you can see throughout Christian history, which Williams calls "the
way of affirmation of images" and "the way of rejection of images".