If you are getting exoticas it is worth the extra small chunka change for Coco Naras... But I do use Exoticas still occasionally... 3Kings aren't that bad either for QLs.
The diffuser isn't really needed IMO... you can make your own (just browse the forums how)
&Romman isn't the best shisha to get started with. Even if you have been smoking for awhile. It isn't enjoyable as , say, a 250g tub of an AF you haven't tried... or the almighty Nakhla
I would say go for Nakhla / Starbuzz if you mainly smoke with friends. Even AF is decent. But Romman, you gotta be careful with what you get. I, for example, love Ivory Coast, Orange, Bubblegum & Good Times... Thats all I have found that I like.