I have googles a few but I am not sure. Have a look and see what you think. There appears to be quite a few available.

I'd have thought it unlikely, as Crista Galli is on of the subtropical ones. Erythrina grows in the wild in either tropical or subtropical regions.
I bring mine in for the winter, although by the end of next summer, I may have to consider building winter protection around it outside.

Erythrina coralloides suffers less damage in mild frosts than E. crista-gallii, but will not bloom for at least a year if it is damaged anyway. I don't know of any suitable for northern European winters.