First, your post is probably going to be deleted because you tagged AVNG3 and JLEAG. That should only be done when there is news related to the movie or starbond you are tagging. Putting brackets around a stock's symbol causes your post to be Tagged to the stock and a link to the post will appear on the stock's page. Since any kind of news (in the form of a Tagged post) will cause traders to buy/sell a stock, tagging without actual news is frowned upon and can be considered manipulation.
In the image you provided, yes the "current value" is the current price.
No, the number of shares a movie or starbond has does not affect it's price. Trader's buying, selling, shorting and covering shares does move the price.
Yes, shorting a stock affects the price. Buying shares and Covering previously Shorted shares will cause the price to rise. Shorting shares and Selling previously Bought shares will cause the price to fall.
Once a transaction has been made, it has no further effect on the price. If you buy shares of a stock, the price will not move again until another trade is made. Just holding shares does not cause the price to change. So in your question about AVNG3 versus JLEAG, the number of shares held long and short makes no difference and has no effect on their prices.
A final suggestion, there are some HSX Leagues where experienced players help new players learn the game. Leagues are under the Community pull down menu at the top of every page. You can still post questions (but I would suggest doing so under the Playing & Trading Strategy section in the future) and will get some help in the forums, the leagues are another source of help. I recommend RazorHawk's HSX School, you can apply to join it here: http://www.hsx.com/league/view.php?id=265