I'd like to know the elements that generally make up a great power
baseball hitter. It seems that quickness and vision are just as
important, if not more important, than strength. But would like to
know more. **This is not a steroids question **

Here are my thoughts about it. Look at Albert Pujols.

1. Strong: First of all, you have to be strong. If you are not, you
need to work out. If you are willing to work VERY hard and keep up
with a workout every 2 to 3 days, then you need to get a weight bench.
You can go the cheaper way by buying dumbells (You can get them at any
sporting goods store, even walmart) at anywhere from $3 to $100. I, at
first, got dumbells. When I realized that I wanted to start a tough
workout and work hard to get more power, I bought a weight bench. You
can get these from $50 to however much you want to add on. I found a
great deal on my workout bench at Dick's Sporting Goods
(dickssportinggoods.com, I have it in my area, but the website doesn't
have many specials) for only $100, which inclued a FitnessGear workout
bench with the barbells. If you want to pay more, you can get other
add-ons, but most of the power you will gain will be from the
barbells.

Also, you can get a standard weight bench or an olympic set. If you
are going to ever bench more than 100, you should probably go with the
olympic set. This is made from tougher material and it can hold much
weight. I have an olympic set, and if you are planning to workout in
high school (If you are just 13-14 right now) they will most likely
have olymic sets there.

2. Stance: Most great power hitters have good stances. Take, for
example, Albert Pujols. He keeps his weight back, and has a wide
stance. Andruw Jones also adjusted his stance from barely bending his
knees from little league to 2005, and when he widened his feet last
year, he led the majors in homers. When you stand straight up and make
a stride, your head moves, which causes you to not be able to see the
ball well. With a wider stance, your stride will just be lifting your
foot up and putting it right back down, almost keeping your head
completely still, letting you hit the ball better.

3. Diet: This is also important if you are going to work out. You
should eat 1 ounce of protein every day for every pound of body weight
you have. You can get protein bars at most places too. You need
protein mostly in the morning with toast or cereal, after your
workout, (your protein bar or something like meat if you workout
before dinner)and before you go to bed. (Usually just a small snack
like stringed cheese or some other dairy product) Proteins build up
your muscles after workouts. Make sure you have a good diet before you
workout.

Other than the things you stated at first, that is just about it. Keep
practicing with someone pitching to you, or if you don't have someone
to pitch to you very much, I recommend the Hit Away. (search it on
google)You wrap it around a poll and when you hit it it wraps around
the poll or tree and comes back for you to hit again. Other training
aids will also help you too.

There is no question that quick reflexes and good vision are as
important as strength to a power hitter.  Without either, a power
hitter's value is greatly diminished because he won't make good
contact often enough to maximize his productivity -- in other words,
he won't make the most of his strength as often as he could.  However,
there are other important factors.  In his book "The Science of
Hitting," Ted Williams, who is considered by many to be the greatest
hitter ever and who was famous for having superior eyesight, said that
what separated him from other hitters was not his eyesight but rather
the discipline not to swing at pitches that he could not hit well. 
While Williams was not a pure power hitter, he did lead the American
League in home runs four times and hit over 500 home runs in his
career.

Another characteristic of great power hitters is the frequency with
which they guess correctly what kind of pitch the pitcher is going to
throw before he throws it.  The worst swings you will see in a
baseball game are the swings of batters who guessed about the pitch
incorrectly -- either about pitch location or about the type of pitch,
or both.  Correct guesses are the product of situational understanding
-- the score, the count, the presence and types of runners on base,
the number of outs, the pattern of pitches thrown to the batter so far
(in a particular at bat, in the game, maybe even over the course of a
series), the pitcher's strengths and weaknesses, and the hitter's
strengths and weaknesses.  Situational awareness can make a good
hitter better.

Finally, the mechanics of the swing are important.  A great power
hitter's body is like a coiled spring as he prepares to swing -- his
hips and arms are cocked and the energy in them is prepared for
release.  The rotation of his hips and the extension of his arms then
provide for the greatest conversion of power possible and if he is
able to hit the right part of the ball with the right part of the bat
(the result of keeping the head still, good hand-eye coordination, and
lots of practice), he succeeds.

All other things being equal, a stronger man will swing a bat faster,
have better bat control, have more time to decide whether to swing or
not, and hit the ball farther, but there are many things which may not
be equal.