Is it bad luck to be given something to use in the house that belonged to someone who was nifter?

No problem, there are those who have the custom not to wear just the shoes of the deceased but it's based upon R. Yehuda HaChasid who isn't generally accepted as halacha (rather as mystic stringencies), but by his family and not the mainstream poskim. R. Moshe Feinstein adds that even they are stringent only if the person died from a contageous disease, but if you know that he died of something else, it's no problem to wear those shoes. In short, no problem whatsoever, and to the contrary, the halacha tells us to say the "Shehecheyanu" bracha upon taking something from the house of the niftar.