By Accents, Definite articles

Yes, the definite article can be used with nouns of both types, "Pour the water onto the tea" – "water" and "tea" are pure uncountable nouns.I don't think so. Maybe we have to struggle a bit to learn to pronounce some sounds, but once grasped, it is not difficult...

I have been told that the accent of Russian is such that Russians have to struggle a lot in order to speak good English. Is it true?

Beg to disagree there Greg. In the past some 'H' words were pronounced without the 'h' - hotel and historic, for example. So they took 'an' as the indefinite article. Other h words have always been pronounced with the 'h' and they take the indefinite article 'a'. I'm sure you wouldn't say 'I...

I thought, Clive, that there was also the issue of whether the accent is on the first or second syllable. We say 'a history' but 'an historical'. My guess is that it would be 'an Hispanic'.