The stroke ....
The pumping of the arm with up and down motion of the upper arm (elbow up) when stroking is called a 'HullyGully' stroke, and although some young guys think it looks cool, will break down over time or when playing for more money than they are use to ... The upper arm is not suppose to move, hence the pendulum swing of the lower arm.
I agree, start with textbook stroke, and try not to stray much from it. Mika was a good example, and so is Johnny Archer.
It never ceases to amaze me the number of people that try to play pool without learning the basics first. That's like taking a test without studying for it.
A world of knowledge about anything is a ladder, and you have to start with the bottom rung first.
When I first decided to learn pool (at 14), I studied it for 6 months, watching all the best players in town play, picking up 2 or 3 shots they did better than anyone else in town, and how they did them. plus I studied 3 books on Pool to learn the proper approach to take and learn the proper basics to the games.
I did all this for 6-7 months PRIOR TO EVER PICKING UP A CUE. I like Pool immediately because I have always had a thing for numbers and math, it didn't depend on physical size (I was little growing up, and most sports size does matter), and it just gets in your blood. Besides 6 months after starting to play, I was a 5 speed, 6 after 1 year, 8 after 2. Most of all, I can not stand to be bad at anything, I have to be in the top 10% in everything I do, and better than that if I can ... It takes motivation, drive, and intelligence to be a really good Pool player, sometimes that intelligence comes from the streets, and sometimes from schooling. I have always had an insatiable curiousity
(gets me in trouble sometimes ...<grin>) to know how everything works.
That basic drive will help you become better.