Audrey Said:

Why are so many Hindi words written in English?

We Answered:

Hindi is not the official language for the whole india. But, english is the link language for the whole india. so, the hindi words are written in english. The tamilnadu govt is adopting only two language formula. the english and tamil only the official language of tamilnadu. Though the other states in south india adopting the 3 language formula, but not showing much interest on hindi. Hindi is the language known to some northern side of india. Hence the reason.

Alma Said:

When Hindi words are written in English, what do the non-English symbols mean?

We Answered:

They are there because Hindi has more distinct sounds than English. For instance, "bh" doesn't really do justice to the sound at the start of the word "bharat". So they developed a standard way to represent the extra sounds in print, by annotating existing English letters.

This article will provide more details: http://en.wikipedia.org/wiki/Hindi-Urdu_… but to really understand I would recommend that you get an audiobook (not a novel, but a "learn Hindi" book that comes with a CD). A lot of times the differences are difficult for a non-native speaker to even hear, much less try to immitate.