Is there any used shop in Zagreb?

Hey, guys.
I am supposed to arrive Zagreb the day after tomorrow, and I will stay there for three months. It is true that I am already worried about living there a bit.

I would like to know if there is any secondhand shop for some kitchen supplies. Plus, is there any bicycle rent shop? I hope so because I think riding the bike is the best way to commute from home to my workplace.

It will be great if somebody can let me know about this question! Have a nice day.