Short answers, pulled from the story.
Russian leadership decided to return Crimea to Russia in February 2014 following the Ukrainian revolution. Pro-Russian separatists took control of the peninsula within weeks without insignias before the Crimean parliament announced a referendum on the 6th of March.
The Russian ruble entered official circulation on the 24th of March 2014 with parallel use of the hryvnia permitted until the 1st of January 2016. By the 1st of June 2014, the ruble became the sole legal tender for all transactions across the territory.
The Fund for Protection of Depositors paid out over $500 million to 196,400 depositors by the 6th of November 2014. This occurred after eight months when it became impossible for clients to access deposits from Ukrainian banks following their closure.
Simferopol International Airport received modernization starting in 2017 with a new terminal opening in April 2018. A high-tech security fence marking the border with Ukraine was completed on the 28th of December 2018 while the Crimean Bridge opened for road traffic in 2018 and rail service began in 2019.
United Nations monitors present from April 2 to the 6th of May 2014 reported concerns about treatment of journalists and ethnic minorities. Journalists and activists opposing the referendum faced harassment and abduction while fifteen persons went missing since March 2014 according to Human Rights Watch.