Absolutely not. Klett Langenscheidt is a publishing house. Uploading or downloading copyrighted PDFs without a license is piracy. While thousands do it, there are real risks:
It depends. If you find a completely free, downloadable PDF of the full Kursbuch (not a sample), it is almost certainly illegal (copyright infringement). Klett Langenscheidt owns the rights, and they have not released the book into the public domain. netzwerk a2 kursbuch pdf