Do I have to unpublish and delete my hubs before going for reprint/republish on other media?

I would suggest deleting the hub before publishing with the online magazine. As for the print I suppose you could give credit to it being also published on Hubpages.com. The point of deleting before submitting to the online Magazine is the risk of having it marked as duplicate by Google and other search engines.

Some magazines also request you not have your work published elsewhere.

This is a good question I've been wondering about myself Vinaya, by the way, congratulations on having your work accepted for publication elsewhere, good work!

You could also edit/tweek your hubs on hubpages. That way you do not have the same hub anymore which you have given for publication.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.