Just from what I've read, I would say that MAYBE you might have sold yourself as being desperate. I agree with forever21 and you might not want to say "bigger is not necessarily better" if it doesnt make sense based on the company size with whom you are interviewing. Also, don't mention taking a paycut if that doesn't come up. Volunteering that info may lead your interviewer to think you are telling that to every company you interview with. This could make them think you'll always move on if something else comes up, or that you don't value the quality of work you are capable of. If the interviewer asks you about your salary requirements, you should already have done research and know what is acceptable in that industry for that area/city. Give them a broad range and back it up with your reasons (I.E. because you have no experience or because you know similar companies are paying within THIS range). Also you might mention that you are flexible based on the company's employee benefits package. This is a huge bonus because most employers only contribute the bare minimum to medical insurance and small companies may not even offer any.
Good job talking out the math problem. You definitely want your potential employer to know you know what you're doing.
If the HR personnel wraps up the phone conversation by asking you if you have any questions, you should ask them what the next step is and when you can expect to hear further from them. Ask this after you ask any job-related questions. This signifies you're satisfied with the conversation and ends the interview neatly. Good luck! I think it's awesome you're researching tips to do well on your next phone interview! Also, dont take it personal all the time. The economy is down and many employers can't afford to hire someone or even replace a position for that matter. You'll be fine when you find the right company!