i doubt there is an exact word for Hello but its more like how r u or stuffs like that but a close one to hello would be : "salam" and usually its chained with how r u (kaisi hain aap /khariat se hain )
oh only the letters and the words of Urdu is similar to arabic the grammar and the way of speech is close o Hindi , so in my Op Urdu is a very superior language i doubt more than Arabic but sure more than the other i know (aprt from arabic) and the poetries on Urdu r supposed to be masterpiece as well. i dont know much abt the poetries but i heard that almost an unparalleled poet exists in urdu lang i think his name is Iqbal