I've not actually seen any of these films, and so I'm fairly tempted to get the collection. Of most relevance here is obviously Sign of the Cross, the now infamous "early Christian" film which provided the necessary impetus to get the Hayes production code off the ground. There's obviously some common ground as well with Cleopatra and The Crusades, two stories which have been fairly poorly represented on the screen. The most famous version of Cleopatra is the 1963 Liz Taylor and Richard Burton version, whilst the lost, Theda Bara version from 1920 seems to be the one otherwise best remembered. Similarly there have been relatively few movies on the Crusades. Last year's Kingdom of Heaven being something of an exception. Peter Chattaway has previously discussed some of the other films that have looked at those events.
As for Four Frightened People and Union Pacific I know very little other than what it says on the Amazon & IMDB.