What to read
1. Ofcourse all the papers on the Reading List. Make notes, 2 versions : one you want to read 2 weeks before the qualifiers, and a super condensed one that you'd read the day before the quals. Forget the evaluation section. Look for when the paper was written, the problem and the solution. You dont have to remember the details.
2. The Synthesis Lectures on Computer Architecture edited by Prof Hill is an awesome collection to read. Spend atleast 30% of your time reading this. When you look at a paper, read the relevant section (I used spotlight on my mac to search). For example, the notes on transactional memory has a all-you-need-to-know summary of SLE and LogTM. Access to these books are free from a UW IP.
3. Wikipedia. Example : Branch Prediction Look for bullets, advantages/disadvantages comparisons etc.,
4. Know your professors : attend every class they teach, youtube and research.microsoft.com has videos. Videos have research summaries, the problems they like to work on and approaches to solutions. Read this white paper.

How to study
1. Look at at-least one question paper from the previous years before you start.
2. It might help to join a reading group.
3. Solve as many question papers as possible : writing/thinking for 4 hours is much more difficult than you know. Practise! Get feedback from your friends in the 6th floor.

What to write
You will be told to make notes on page 1 of every answer book : a summary/organization of thoughts. I strongly advise you not to do that. I think it is enough if you pick the top 3 points and give elaborate answers. Comp Arch Quals is all about analysis. As long as you are not off the answer by a mile, a well written paragraph analysing one solution will fetch you more points than 30 bullets. Again this just my view : please talk to people in the 6th floor.