And while I have knowledgeable eyes looking at these, here's one more from the side. I'm assuming the one burn on the leaf in back is sunburn (I picked this up about a month ago from the local nursery and I'm sure it wasn't used to the 7+ hours of sun; the fence in back protects it from the harshest sun after 3pm; temps have been 80's and 90's F here in NorCal).

The buckle on the leaf on right -- caused by the same pest above or something else?

And the little white "crystals" here & there on new growth -- is this normal?

Thx again for any help on this. I'm new to plumerias this year and it's definitely a steep learning curve.

The little insects are thrips. An ugly little pest that is not as damaging as spider mites, but can cause quite a bit of trouble too. In the beginning, it's mostly little silvery spots you see on leaves. If it gets bad, the leaves of the entire plant will appear bronze-silvery, creating growth problems because the amount of photosynthesis the plant can perform is reduced due to the lack of chlorophyll.

They thrive in warm to hot areas with low humidity and no precipitation, such as your typical NorCal summer, or indoors. Mist the leaves every once in a while in the morning or evening - insecticides are available too if it gets severe.

The "crystals" are most likely dried up sap (white) or excess sugars (mostly clear). If the first, this can be caused by thrips, but can also be due to other physical damage. If it's the latter, it's nothing to worry about.

As for the damage to the leaf, doubtful thrips can cause this... looks more like some other physical damage early in the development.