first of all - those 'workers package' will certainly make things easier for you, but yeah...they're run by people who don't just do it for the love of it, but also because they want to make money.
at 18, you will definitely be at the younger scale of the worker's community, but that's not a reason to be put off by I think. as for being attractive, if you want to be a model or a dancer it will of course help if you're a super stud, but as long as you're not the hunchback of notre dame, you'll be perfectly fine to find a job I think. it's much more about the attitude you show. ibiza is very international as you correctly write so no one will care if you're not looking swedish even if you've got a swedish passport. your nationality doesn't really matter all that much in ibiza (but the fact you have a swedish passport will at least enable you getting a NIE which is important to work legally).
I don't think you'll use kurdish a lot. english every day, no matter where and what you do. swedish every now and then. spanish lots of course if you can speak it. you'll find a job in mid june - just be open minded. also, especially if it's your first season, you might find yourself trying out a few jobs until you've found something that suits you.
as for living - 1300€ is a good amount to start with. book the cheapest hostel for a few nights, meet people, find a place to live. again, if you don't like who you live with, you can always change at some point. in many respects the first season is the hardest because you don't know anyone and everything's new.
lastly, almost no matter what job you do, even if it's got nothing to do with the nightlife industry, you'll get to know people that know people that will be able to sort you out for your club nights. maybe not for all of them and everytime, but contacts is the main word.