First off, your query shouldn't be over one page! Not 4, 6, 9, just 1! Agents get so many in that they don't have time in the day to go through forty query letters with 6 pages each! Keep it simple and don't over do it.
Do Agents read them? Yes! I'm only a junior agent but I can tell you, working for Marisa Corviserio, that we do read them. But! If it is boring, untasteful or something we are not interested in, then no we toss it to the side. Your query has to bring a short synopsis to us, in a page, with a short paragraph about yourself to us, also. It's A LOT to get in one page I know, I know! But, it's possible.
At the beginning you give your hook. This is curcial. It should be something that makes the reader what to keep going. They should say after reading the first line or two "WOW I HAVE TO KNOW WHAT IS GOING ON!"
Example: (This was my hook in Fighting Destiny)
When Molly Drowns is forced back to her fearful past, she finds herself face to face with her despised but desirable destiny.It has to be something that will stick, and will get the reader interested. Take the idea of your book and work with the theme. Something will come to you, I promise.
Secondly, you need a mini-synopsis. This is when you take your synopsis and shorten it, A LOT! Take the main points of your book and list them (this is what I did). Once listed, go over them and write them into a brief summary. It helps. Also, do not leave bad endings or unhappy endings out of your query. Because, some agents do not represent unhappy endings. If the guy dies in the end, tell us, we NEED to know. (P.S. I'm not a fan of unhappy endings.) Boo!
And finally, ta da, something a little easier! Yourself. You should know a little about yourself, or enough to know what to put. We need to know your name (duh), where you went to school, or are attending, things you love to do, and anything you've ever published. This is something that jumps out at an agent, that you have been published before, this might be publish worthy, also. :)
Another something that is important, SPELLING! That's why autocorrect was made. USE IT! Have someone (not related to you) read over it, and help with the flow of the query. Also, spell query right. :) That's a good thing to do.
Some other hints for you during your mini-synopsis. Give us the time period and location, the main characters name, their goal, their trouble they have to overcome and a conclusion. We aren't the audience, we need to know the ending. This isn't your blurb, this is for someone that needs to know the book, and the ending, to see it we want to represent you!
So...that was just some thoughts on queries. Hope it helps!