I just posted a thread yesterday on the palms forum and posted a pic of some of my palms I just put up in Air Pots and Smart Pots. I am interested in the answers to your questions as well.

Here is a link that might be useful: Palms in Smart Pots

1. Couple of rough tests for shifting. Gently try to lift the plant by the stem. If the plant starts to pull loose, it is not ready. If you can lift container and all, it may be ready for a shift. Another sign with some containers is if the plant lifts out of the container but the entire soil ball holds together... Shift. In general, the sooner the shift, the sooner that plant gets a jump on any competition.

2.The "4 inch rule" applies to most plants... A shift once a year does a pretty good job of maintaining that growth momentum. For larger trees, say 3 inch diameter and up, the "inch rule" probably inches to 6 or more inches per shift.

Hope that helps!