Sounds like the GE Reveal CFLs that you are using, are their new "Bright from the Start" bulbs. It will say "Bright from the Start" on the upper right of the package. In order to minimize the start-up time of CFLs to get to full brightness, they developed a bulb that has a small halogen bulb within the CFL bulb. At turn-on the halogen comes on as well as the CFL portion - after about 30-60 seconds the CFL portion is suppose to be at full brightness and the halogen turns off. This does create a noticeable "dimming" effect but the bulb now is suppose to be at the same brightness as any similar CFL.

If "powder puff" refers to Calliandra haematocephala or C. surinamensis, this is really a shrub rather than a tree and far too low growing to be any attraction to woodpeckers :-) I agree with Mike that it was a older, dead cane that has become infested with insects that feed and process dead wood. Not really any big deal but suggest removing that cane at the base of the plant. That should encourage some newer basal growth as well as remove any future insect issues from migrating into the healthy stuff.

Yellowing leaf margins usually mean a nutritional deficiency. Try a spoonful of epsom salts.

There are several possibilities. First I'd check /very/ carefully for a root mealie infestation. A few years ago some of my streps were showing similarly yellow leaves and Dale Martens hopped right in and said they probably had root mealies. Sure enough, they did! May not be a bad idea to repot, washing the roots very carefully and sterilizing your pot or using a new one - and adding insect granules to your fresh mix. You should be able to see root mealies if they are thick but they may be very difficult to see and easily mistaken for perlite if the infestation is not heavy. The other suggestions here are also good about feeding, light, temperature, etc. So check them all and make corrections as necessary.