Yakumo,
USA allows you to have dual citizenship, you cannot have triple citizenship that's first off. I have Pakistan's nationality and I can have US. If I wish to get Canadian or Aussie citizenship, I'd have to relinquish either Pakistan's or US citizenship. As far as test is concerned. In the book, there are 100 questions along with the CD, which is audio cd with 100 questions with their answers, listen to that CD twice, and read the book's question's and answer twice, and you would memorize pretty much everything as I already knew a lot about American History. Test is Hard
"Heck NO" USCIS officer would ask you 5 to 6 questions in a row, first he would take oath from you, and then he would ask you 5 to 6 questions randomly out of 100 question, if you answered them correctly, he would stop asking questions. He would ask you read this sentence "Who can vote" and he would ask you to write "Every citizen can vote" is it difficult????? I don't think so. Then he'd ask you the questions from your form, that did you ever claim to be US citizen, did you ever vote? the answer is of course No as without being a citizen you can't claim neither vote. Take your signatures, ask you that your name's spelling is correct as it has to be shown on your Citizenship certificate, he'd take 2 signatures on the corner sides of the pictures which are to be affixed on your citizenship certificate. once you are done, in an hour or so, you'd be handed oath ceremony letter. I had my interview last Monday June 6, 2011, as I can talk a lot, so USCIS officer took the longest time with me as soon as we completed all the formalities, we were shooting the breeze lol.
It's easy as PIE, yeah college test in Texas like my college test which is called Compass test for lone star college is hard as turtle's shell, this citizenship test is piece of cake. So don't worry and good luck.
**As you said you have dual citizenship, You cannot be US citizen unless you relinquish/give in either British or Aussie citizenship.
Go through this link too.
http://travel.state.gov/travel/cis_p.../cis_1753.html
Good Luck
Mody