I think there is some truth to most of the shown areas, but they mix up official annexiation plans, personal proposals of single agitators and the discussed split-off of independent states (such as Finland, Poland and the Ukrainian). Also, there was always a great confusion about such plans. E.g., the map of 1918 shows mainly Ludendorffs personal opinion which was opposed by the official high command (Reichsleitung). In general, the higher military ranks (and of course the industry) favoured more radical demands to keep up moral. On the other hand, after 1916 the social democrats plans for a peace whithout any annexiations or reparations was quite popular, particularly among the work staff and the lower military ranks.
I guess the German territoral demands were never really defined by the official representation, except for the rather moderate "September program" in 1914 which did not last very long anyway. But for the allies it was shurely quite advantageous to publish whatever the most radical proposals were, regardless of their political relevance.
The african plans for a territory called "Deutsch-Mittelafrika" had their origins in negotiations between Germany and England in 1913. Portugal was almost broke and both states planned to divide the portuguese colonies up. Germany tried to achieve a complete east-west connection, but England prevented this for its own interests. During the war, the old plans were brought up again and extended by parts of the French and Belgian colonies. The project would have probably been persued in case of a victory over these countries. So this may actually be the most correct part of the maps. I remember reading that Mittelafrika would have been sort of a German counterweight to India which was a great prestige object for England at the time.