Short answers, pulled from the story.
Isao Takahata and Hayao Miyazaki traveled to Maienfeld in Switzerland during the summer of 1973. They spent two days walking through the mountains that would become the backdrop for their new animated series.
Yōichi Kotabe joined the production team as the character designer and animation director for Heidi Girl of the Alps. He removed the pigtails from the initial design after a Swiss librarian advised him that a five-year-old mountain girl could not tie them.
The animation studio responsible for Heidi, Zuiyo Enterprise, split in 1975 into Nippon Animation. Nippon Animation employed the anime's production staff while Zuiyo retained the rights and debt to the Heidi TV series.
The feature-length film edit of the TV series released in March 1979 was engineered completely by Zuiyo. There was no additional involvement from Nippon Animation, Takahata or Miyazaki because they had already left both companies by 1979.
In Spain, the series debuted on TVE on the 2nd of May 1975. It became one of the most popular anime of all time there despite the theme songs being kept in Japanese for the broadcast.