Miami absolute nightmare I'm afraid, queued for ages and then had to have not just fingerprints done but eye scan as well, and they are strict with the suitcase allowance. The amount of people on the way back who were transferring clothes from one case to another was unbelievable but the cruises are fantastic so worth the hassle.
American customs I am afraid, but lately there have not been the same number of problems reported as in the past. Just make sure the emigration/custom forms you get on the flight are completed properly, if you are not sure ask a fellow passenger or one the attendants. If you have a biometric passport it should help but don't think this is stopping them taking your photo's and fingerprints.