REC

El Gran Steep

According to the wikipedia page for REC, http://en.wikipedia.org/wiki/REC_%28anime%29, every episode is based on a different Audrey Hepburn movie. Just an FYI.

Apreche

According to imdb she was in 30 movies. If they cut out the 4 worst movies they've got a 26 episode show. Good thinking on their part.

Katsu

Actually, the series is only 9 episodes long. They could have stretched it out for 26, but it seems they decided to go for fast impact.
The wiki article says that the manga is still ongoing, however, so I hope that I can find it somewhere.

Ametto

Its a really fast watch. With 9 episodes at around 10 minutes each, it's equal to the size of an average movie.