The name "Raju"

Q: A male whose name is Raju, what does the name Raju mean? Is it permissible to keep the name or should the name Raju be changed because I
heard Raju is a Hindu name?

The name "Alayna"

Q: Is it permissible to keep the name alayna الينة as in the root ل ي ن not علينا the preposition. Alayna is derived from layyinah which is mentioned in surah taha. Alayna is also mentioned in surah yaseen. Is Aleena or liyana suitable names?

Conditions for one's duas being accepted

Q: I would like to know, sometimes our duas are not accepted by Allah, we don't get solutions for our problems, even after doing lot of dua. Is there any particular method in asking for dua, or is it because of the sins performed in the past knowingly or unknowingly? I know nothing will happen to our wish, but still is there any particular thing to be done, so that our halal duas get accepted?