The nature of the internet is that when you ask for opinions, you get them. Right or wrong, you get opinions. If you don't feel they are valid then ignore them. I don't think you'll find any scientists here doing studies on the subject, so you might well be better informed than most of us.

I can answer a few things:

Influenza ("The Flu") is caused by the influenza virus.
Common colds are caused by rhinovirus.
Vit K ensures that calcium is deposited into bones, not arteries.
D3 needs to be taken with fat. It is a "fat soluble" vitamin. You can Google that for more info.

vitamindcouncil.org is a good source for info about D3.