Renting a flat in Warsaw (pricing, options)

Hi, I'm a student from Ukraine, and I'll study in Warsaw from the next year because this year I couldn't find any proper dormitory,and missed my friend :( So next year I'll come with him, and we want to rent a flat :)
I don't know Polish language, so that I cannot search for flats at search sites, but I'm willing to learn this language, and start to learn from next week :) So for now, I have several questions. And, would be very thankfull if you could answer :)

Can you recommend me something where I can find a flat (not very far from Palac Kultury i Nauki)? And prices?
Is there some people that offer their flat at ul.Chmielna? Can me, and my friend live with flat owners?

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Please write me to solha@yandex.ru
Thanks :)