A) How much does the average astronomer make and what are the health benefits, opportunities for overtime etc.?
B). What are the chances for promotion in the field, i.e. to become boss astronomer?
C) What courses do I need to take, including in college?
D) What is the typical work day like?
First, no one I know goes into astronomy for pay, health benefits, paid overtime or the like. You can probably find better options in a corporation! If benefits and remuneration are one's primary concern, it's probably better to re-think his or her choice of career. The average astronomer's salary, by the way, depends on many factors, not least is the institution with which one is affiliated, and the seniority of position. But most base pay for the starting astronomer (associate professor, say) is in the range of $55,000 - 75,000 per annum.
'Promotion' is a loaded term, because it implies that those in senior positions will soon retire - to make way for younger staff. This doesn't always happen, or at least as quickly as the younger staff want it in a field like astronomy. For many, it may be necessary, therefore - to work only in 'adjunct' or part time positions with few or no benefits. People understand this when they go into the field. (Especially as government funding for many astronomy projects has gone way down in the past 6 yrs. or so)
The main promotion criterion is how many papers one has had published, and the quality of research. The key indicator in that regard - if one is university based - is getting tenure. Tenure may be conferred based on quantity and quality of research papers produced, but alternatively - in terms of academic works, books published.
Regarding necessary skills, of course, a great deal of mathematical and observational skills are needed, and computer skills certainly are indispensable - mainly since so much numerical modeling is done these days in astronomy departments. Perhaps above all, one needs an abiding curiosity in nature and the larger universe.
Re: education and skills needed - these are usually formidable. In high school for example take all the math and physics courses available. 'Astronomy' is actually quite a large area to try to explain at one time because it includes a number of large sub-areas:
astrometry - the study of star positions and how these change over time with celestial coordinates
celestial mechanics - the prediction of the future positions of the planets, Moon
stellar astrophysics - the study of the physics of the stars, and their evolution, changing properties
solar physics - the study of the Sun, its physics and properties, as well as terrestrial effects
galactic dynamics - the study of the dynamics and physics of the galaxies and galactic clusters
cosmology- the study of the large scale motions and expansion of the universe including the derivation of its past properties from currently observed phenomena.
Each one of these would probably take several large books to even survey, far less 'explain'. What this shows is that like many other scientific disciplines, astronomy has grown and developed beyond simple description or being one simple science. When people become astronomers today, in fact, they have to specialize in one area, say solar physics - they can't just do 'astronomy' - it's too much!
The core courses needed for a specialist astronomy (B.Sc.) degree include:
Math: Calculus, Advanced Calculus, Linear Algebra, Differential equations, Complex Analysis, Numerical Analysis.
Physics: General Calculus-based Physics (with labs); Electricity & Magnetism, Thermodynamics, Classical Mechanics, Quantum Mechanics, Statistical Mechanics, Optics, Plasma Physics.
Astronomy: Geodesy & Astrometry (coordinate systems, fundamental star positions and determinations); Celestial Mechanics (application of classical mechanics to celestial motions), Stellar
Astrophysics, cosmology, radio astronomy, Stellar evolution, Binary stars, astronomical observing and measuring.
The typical day probably then begins with giving a class, say in astrophysics, then holding at least one hour for office time - to allow students to come in and ask questions.
Then there may be a need to prepare a lab - and if not, one can make use of the campus library to get caught up on the research - and also - look to preparing one or more papers in one's field. In general, research astronomers are allocated more time for this (as opposed to teaching) because it is expected they will publish more.
Lots of time may also be spent going over data - say obtained from a telescope or other facility. It may also be necessary to go to the Observatory and re-do photographic plates, or spectra if it is thought better resolution is needed. (Better optical results to determine what is going on with the objects under study.)
If one is. senior academic, then supervising research students will also be part of the day's duties.