Spanish verses spanish
Will I have a problem making myself understood in Spain when so many words are differant, eg Coche/ Carro. periodico/ diario. nosotros/ vosotros, and there are a lot more. Will the Spanish nationals still understand if I use South American by mistake?
Yes you will be understood. The people in Spain watch many Latin American movies and telenovelas. Of course, there may be weird situations from time to time where a word comes up that isn't understood.
I think may be like the US and the UK, e.g. you have "lorry" vs "truck", "lift" vs "elevator", "pavement" vs "sidewalk", "fag" vs "cigarette" and many many more.
And the accents are completely different.
Yet they seem to have no problem understanding each other.
And of course even different regions within countries have their own dialects, for American English just look at the South vs the East Coast and the West Coast and there is noticeable variation.
So I suspect the people in Spain are used to hearing different variations of Spanish and shouldn't have a problem.