Re: what do need for a Mehndi?
No, you better look for it in europe? Lols.
Ofcourse this is where you will find all this stuff better 
You can also get a songs book i suppose otherwise elders in your family can help you out with the songs. Usually people have dholak parties before mehndi and that’s where they practise those songs and they are easy to memorise. As for decor, if you want to do it yourself then find some references from net and you can always hire people to help you out with it. Or just go to a event management team and they wl do it for you 