O Brave New World...

I don't know if this will help, but I thought I'd point out that रहा/रही/रहे rahaa/rahii/rahe are forms of the verb रहना rehnaa "to remain".

Hindi (as well as some other Indic languages) have the somewhat unusual feature known as compound verbs (http://en.wikipedia.org/wiki/Compound_verb), which you've seen in other places such as बिल्लियां आ जाती हैं billiyaan aa jaatii hain "cats come". Here आ aa is the stem of आना aanaa and जाती हैं jaatii hain is the plural feminine present imperfective form of जानाा jaanaa "to go", so you get what at first blush appears to say "comes goes". It takes some effort to "forget" what जाती usually means because here it doesn't mean "goes" at all -- it adds "color" to the verb it's modifying, in this case adding a sense of definiteness (or completion, if this were past tense, i.e. आ गयी). In other cases it might change the meaning entirely; the Hindi section in the Wikipedia link above has a couple of examples of this.

Compound verbs are rather complicated to explain, and probably even harder to learn: Usha Jain of UC Berkeley, for example, doesn't even try to explain them in her widely used textbook for first year Hindi, covering them instead in her recent Advanced Hindi Grammar. But it's an absolutely central feature of the language, and one can barely get by in Hindi without compound verbs.

Hmm, there I go again. Perhaps I should start a Hindi-Urdu blog for such ramblings rather than burden you with them all the time. I've already registered hindi-urdu.org (www.hindi-urdu.org), so there's a good place for it. Now I just need to get the site up and running.