What's your question? Ask

Cutting them back to the ground is one possibility. If by chance some are still alive, they should grow back next year.

Here are some other options. Removing dead shrubs should be easier than live ones. Even if you can't get all the roots, completely dead ones won't grow back.
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/removing-oleander-bushes.htm

unfortunately, yes, these can be a bit invasive. If you suspect that something could be damaged then you can move it, or kill it off. Here is an article for more information: https://www.gardeningknowhow.com/ornamental/shrubs/oleander/removing-oleander-bushes.htm

It is best not to take more than a third of the plant off at a time. This article will give you more information: https://www.gardeningknowhow.com/ornamental/shrubs/oleander/pruning-oleander-shrubs.htm

Yes, these plants don't seem to tolerate freezes at all. Your best move now, would be to propagate some of this in container and bring it in when freezes are expected.

This article will help: https://www.gardeningknowhow.com/ornamental/shrubs/oleander/growing-oleander-in-containers.htm

Yes. They can stand that temperature just fine. I think keeping it under horticultural lighting will be a good idea. This will ensure that it survives. This article will give you an idea of how to care for these: https://www.gardeningknowhow.com/ornamental/shrubs/oleander/oleander-growing-tips.htm

It isn't necessary to do so, but if you choose to you can follow this guide: https://www.gardeningknowhow.com/ornamental/shrubs/oleander/pruning-oleander-shrubs.htm