i read that shakira learnt portuguese to crack the portuguese market in the 90s. she hasnt released any portuguese albums, but only tracks. were these released to radio or made as singles?

The Portuguese songs are on the album "The Remixes". There's Estou Aqui, Um Pouco De Amor and Pes Decalcos (dunno if spellings are right). I dunno if they were actually released as singles but they were designed to promote Shakira in Brazil.

there also on a Brazilian version of the PD album

Portuguese is very similar to spanish so she wouldn't have found it hard to learn it.

its her second language after Spanish

Portuguese and Spanish is like Dutch and German apparently. If you know one, it's easy to learn the other, even though they are different languages. i think the main difference between Spanish and Portuguese is the pronounciation.