What's your question? Ask

Plumeria yellowing leaves and leaf drop is usually a sign of too much water. Irma caused much stress on people and plants, I hope this plant's damage is all that you and yours dealt with in it's wake. The only thing to do for the plumeria is give it time to dry out and settle back in to the normal routine. Keep and eye on it for secondary fungal diseases which can affect stressed and water logged plants.

You can prune them in winter or early spring before any flower sites would start to appear.It doesn't matter a whole lot if you prune above or below a leaf, but I do prefer to go just above the leaf, typically.

I would apply dolomitic lime to the soil, as well, so that you can be sure your pH is correct.

Here is an article for more information: https://www.gardeningknowhow.com/ornamental/flowers/plumeria/plumeria-pruning-info.htm

You can if you would like, but it isn't completely necessary. There are times when you would normally prune the plant if you wanted to wait until then. If you just want to rid of the dead blooms, then it is ok to cut these off.

Here is an article for more information on the care of these plants: https://www.gardeningknowhow.com/ornamental/flowers/plumeria/growing-plumeria.htm

These can, actually, handle some pretty heavy pruning. You will be fine to cut back pretty hard. This article will give you much more detail: https://www.gardeningknowhow.com/ornamental/flowers/plumeria/plumeria-pruning-info.htm

Plumeria can be damaged by frost, so you should bring them indoors before the predicted first frost in your area. A plumeria could potentially survive in a plastic greenhouse, but it would depend on the temperatures in the greenhouse during the winter. The temperature should stay above 55 degrees for the plumeria to stay healthy, and should never drop below freezing in the greenhouse. Also make sure it doesn't get too overheated in the greenhouse (such as on sunny days in spring).