First, let me address the question of the 1400 vs. the 1800 player. The biggest difference between the classes of chessplayers is the ability to accurately evaluate the position, and form the proper plan from that evaluation. The amount of games a player has played is not really an accurate guide for this. The person who can look at a position and say "I stand better because of this and this advantage" is the player who will continue to climb the rating chart.

When you are talking about the differences between Grandmasters (such as Shirov and Kasparov) we are now talking mostly of CONSISTENCY. Surely the difference in actual chess knowledge between these two is very small. But when you are talking about the Grandmaster level, the difference between ratings is usually factors such as who has the better concentration at the board, who tries to squeeze the tiniest advantage from the position, and in other words, WHO WANTS IT MORE. It is a bit like Olympic athletes....any of the top three runners have the capability to beak records. It is the one who CONSISTENTLY tries to break them in EVERY run he makes that will be the top dog.

The Alekhine's is a very fine opening. I'm not sure what you mean by risky. It has been proven to be very solid, although it's popularity seems to come and go in waves.

I cannot agree with this statement. While defensive techniques are at an all-time high, we are in a time right now where aggressive chess is being played at the top levels. Players like Shirov, Polgar, Kasparov, Kramnik, Kamsky all play highly entertaining games full of stunning attacks. Check them out, you will learn much about the state of the art of attack in contemporary chess.

There is no specific time table to improving your game. It is up to the inividual's talent for the game (how good an abstract thinker is this person?), the resorces available (good books, perhaps a tutor), and the time he or she has available to learn. A common phenomena (all the way up to GM level) is to reach a "plateau" where it seems no matter what, a player doesnt seem to improve. This can be frustrating and also have a negative effect on future progress. Be aware that this happens to the best, and use determination to improve to get over the next "hump". Every player has been though it, so dont ever let yourself think, "I'm as good as I will ever be". There is a saying that the beginner and the Grandmaster both drink from the same fountain. The body of chess knowledge is out there, and it is up to you to decide how much of it you want to learn.