Would "preciso um jornal em inglês" be correct too?
no. use "precisar + de + noun/pronoun".
so what does "preciso um jornal em ingles" translate to english without the "de"?
Without the "de" it does not work...
"DUM" is an accepted contraction of "DE" and "UM," is it not?
It is more common in old Portuguese. Now using "dum/duma" may sound a bit odd or weird, but it's still correct.
Nope, as far as I know, it's not grammatically correct. :(
I've never seen dum written anywhere, but it could be used in spoken language, or in very colloquial texts.
It is my understanding that in European Portuguese, that is how it is spoken, but not written.
Why doesn't it accept 'dum' as an option?
It's also right, but less common nowadays.