No! Please stop asking me this! (Sorry, the rest of the questions below have much more polite answers)
My favorite book for beginners is "The Stars: A New Way to See Them" by H.A. Rey (the Curious George author). It is very well done and entertaining too.
The constellations were invented, not discovered. The constellations are just distinctive and easy-to-remember patterns of stars. Most of the famous ones were invented before the beginning of recorded history. Orion, for example, has a history dating to before about 4000 BC. (see "What are Constellations?" for more info).
All of the stars that have names (about 2-300 of them) were named between 500 and 2000+ years ago. Most of the star names in use today came from Arabic names. These days, all stars are named for their coordinates (e.g NTTS 045251+3016 is one I've worked on) by the IAU (International Astronomical Union).
Picture the Milky Way to be like a big, translucent pancake. We are in it about half way from the middle to the edge on one side. The big strip you see in the sky as the Milky Way is the light from many of the stars in our disk-shaped galaxy. The Milky Way seems to wrap around the whole sky because of the pancake-shape that surrounds us. But because of all of the gas and dust in the galaxy, it is not transparent, so we can only see about 5-10% of the way across with visible-light telescopes (radio and infrared telescopes can see farther through the dust) so the Milky Way appears about equally bright in a band around the sky.
Right Ascension (aka RA) and Declination (Dec) are coordinates which
identify a star's location in the sky. RA is similar to longitude on
the Earth while Dec is like latitude. However, while Dec is measured
in degrees, arcminutes and arcseconds, RA is measured in hours minutes
and seconds. To convert to degrees, multiply the RA by 15 (since 360
degrees divided by 24 hours is 15).
(More detailed explanation)
B and V are measures of a star's brightness through a mostly blue and mostly green filter (respectively). The brightnesses are measured in magnitudes, which are a somewhat complex concept. Briefly, a lower (or more negative) magnitude is brighter and a larger magnitude is fainter. It's on a logarithmic scale though. B-V is an approximate measure of the color of a star (low means blue, high means red).
Finally, spectral type is a measure of the kind of star. They go in the following order: O, B, A, F, G, K, M. O stars are typically the brightest, bluest, most massive and shortest lived stars. M stars on the other hand are often the faintest, reddest, least massive and longest lived. The Sun is a G star, so it is somewhere in the middle.
The letters don't actually mean anything. They were chosen before astronomers really understood stars. The stars were classified as A, B, C, etc. Later, when star temperatures were figured out, they reordered them. The number following the letter is the subclass. For example, within G, stars are further classified from G0 to G1 through G9 from hottest to coolest. The Sun is a G2. The last letter is a Roman numeral indicating the type of star from I (supergiant) to III (giant) to V (normal, but called "dwarf") to VI (subdwarf).
If you need more details, this info should be in any decent high school/college level textbook.
It's due to turbulence in the atmosphere. It's just like how things look wavy when you look over a hot grill in the summer, only on a smaller scale. An even better analogy is that looking at stars from inside our atmosphere is like birdwatching from the bottom of a swimming pool: the ripples distort the picture. That's one of the main reasons why space telescopes, like Hubble, provide such sharp pictures.
In addition to contributing turbulence, the atmosphere also acts like a prism when you look at stars near the horizon. Since the star colors get split into a rainbow plus the turbulence makes the star move around, it can appear like the star is changing color. When I was a kid, I thought I had spotted a UFO when I saw a star do this...
Almost always, you need to graduate from college and get a PhD in Physics or Astronomy.
Just as an example, here's a list of the types of courses I took as an undergrad in college:
4 semesters of post-calculus math
3 semesters of intro physics
2 semesters of quantum physics
1 semester of mechanics
2 semesters of electricity and magnetism
1 semester of computational physics (i.e., computers to solve physics problems)
1 semester of solid state physics
1 semester of topics in astronomy
2 semesters of basic astrophysics
1 semester of astronomical techniques
1 semester of celestial mechanics (planetary physics)
I also took 8 semesters of programming courses, although none of those were actually required for my major.
I spent a good part of my first two years of grad school taking more classes (mostly astronomy, but some physics courses too).
Now, as a grad student, I spend most of my time analyzing data from the infrequent trips I make to telescopes and some data from a variety of space telescopes. I also spend a substantial fraction of my time writing proposals to (1) get time on telescopes, (2) get money to pay for my trips, and (3) to the faculty explaining what I'm doing for my PhD thesis. Besides that, it takes quite a bit of time to write the papers that I hope to get published. Papers take a lot of time to write because you have to do a lot of reading to keep up on what other people have done on similar topics.
That's as far as I've gotten so far, so you'll have to ask someone else what the rest of the steps are like.