O.K., this is my unprofessional opinion. Without damaging the roots too much, I think either way would be fine with proper care. Make sure you use a well drained soil under and around the roots, water in with Vitamin B-1 and super thrive. Planting in a pot would able you to move it inside out of the cold if the temps reach freezing.
Remove the leaves form your cuttings. Some use a soiless mixture ( peat moss, ground bark, pumice and or perilite). Some people use 50% cactus mix- 50% pumice. I got some cuttings last fall and potted them up with a soiless mixture and kept them inside next to a south facing window. They were fine and rooted this summer. Hope this helps a little. Bob

If you are digging up a plant, you will be digging up roots. Therefore it is already rooted and needs only be planted with some water and B-1 and or superthrive to reduce transplant shock. Do not remove leaves as they are used to draw water from the roots,but they may droop because of first shock but should respond shortly. Freezing temps are deadly to plumies so if you get temps below 32 you must take the plants inside. You can use frost cloth and xmas lights for brief frosts but long time cold kills. I would try to wait to cut the branches late in fall or better in about February. Always strip off leaves and flowers before rooting. If flowers form while rooting you can watch the leaf growth and remove the flowers if the leaves stop growing, but a flower on a cutting before rooting is a major drain and leaves suck the water from the stock which is needed to root.

I have a few plumerias I put in the ground this year and am wondering about keeping them warm with X-mas lights. Does anyone have any photos of this? I'm wondering which type of lights I should use. The small lights that you can find everywhere of the old school big bulb lights. I'm thinking the old school light would put out more heat but are much more heavy then the small lights.

C-7s or C-9s throw out a fair amount of heat but can burn the stems where they touch. You could just drape the lights on the ground beneath the plant if you cover it. Heat rises and will be trapped by the covering. If you leave the plants uncovered and have wind, any warming benefit would be lost, I imagine. You can purchase cheap thermostats which turn on at 40 degrees or so (see link below). You might also consider using spot lights which turn on by thermostat.

Where you live though, likely a simple covering would be better than lights?

Here is a link that might be useful: TC-3 Thermocube

Regarding the 4' tall that'll be dug up: is it OK to just wrap the whole rootball/dirt in a trashbag during transport? Will the plant survive in that condition for a day to so, before I get around to potting it?

I responded to the wrong email. Sheesh.

use wet cloth not plastic. you can put wet cloth around it and then put it in a plastic bag but you do not want the roots to dry out. The longer you wait the more chance of shock. I try to prepare the plant location first and then dig up and plant within a very short time. Best for me. Bill