The new "liquid layout" adjustments are not intuitive and you DO need to see them demonstrated. Here are a couple of videos made by Anne-Marie Concepcion for Lynda.com which are available thru Adobe TV:
I hope they help!
CS5 din't have very advanced tools for this. If you're going to be publishing to iPad I would recommend upgrading to CS6
Oops. Missed the fact that Dave was working in CS5!
I totally agree with Bob that you need to upgrade to CS6 for that kind of work. There were major advances in layout adjustment which the videos I referenced point out very clearly.
Thanks for all your help - yes it looks like I need to upgrade to CS6! For now I guess I am stuck doing this manually on CS5!