What element is the final nonradioactive decay product of uranium?
Lead 206 (Pb)
It is uranium that is changed into lead during radioactive decay. Note that there are a number of intermediate steps in the conversion of uranium into stable lead. The uranium does not change directly into lead. The uranium atom undergoes decay, and a radioactive daughter product appears. This continues with radioactive daughters appearing at the end of every step - until lead appears.
What is the toxic radioactive metallic element that occurs in small quantities as a decay product of uranium?
Uranium has a different decay chain/series for its different isotopes. Uranium 238 for example first decays to thorium 234 through alpha decay while U235 alpha decays to thorium 231. Both have different half lifes which can be found on a natural decay series chart for the said element. The thorium in either case then beta decays to another element.