Short answers, pulled from the story.
The 2008 amendments extended the term of the President of Russia from four years to six years and the term of the State Duma from four years to five years. They were the first substantial amendments to the 1993 constitution. The changes did not apply retroactively to the sitting president or the current Duma.
The amendments came into force on the 31st of December 2008, after being published in Rossiyskaya Gazeta. President Dmitry Medvedev signed them into law on the 30th of December 2008.
President Dmitry Medvedev proposed the amendments during his first annual address to the Federal Assembly on the 5th of November 2008. He formally submitted the bill to the State Duma on the 11th of November.
The State Duma approved the bill in three required readings. On the 14th of November the vote was 388 in favor and 58 against; on the 19th it was 351 in favor and 57 against; on the 21st it was 392 in favor and 57 against. Only the Communist Party, with 57 members, opposed the bill at each stage.
Yes. By the 18th of December 2008, the legislatures of all 83 federal subjects of Russia had approved the amendments. Ratification by at least two-thirds of the 83 subjects was required under Articles 136 and 108 of the constitution.
VTsIOM conducted a survey on the 15th and the 16th of November 2008 that found 56 percent of Russians supported a longer presidency and an extended Duma term. Support was lower in Russia's large cities than in the country as a whole.