Actually, they did some recent studies and they have proved that Neanderthal DNA is still alive in people today. They have proven several different strains across the world so the cross breeding was very common
Also, as far as the tallest people I found a list, but the tallest to ever live was robert wadlow. Usually the tallness has more to do with a malfunction of the pituitary gland rather than genetics that you speak of.
http://en.wikipedia.org/wiki/Robert_Wadlow incase you want to more about the tallest man
http://en.wikipedia.org/wiki/List_of_tallest_peopl... - self explanitory