The umbrella poisoning was lifted heavily from the assassination of Bulgarian dissident writer Georgi Markov in 1978. It was also allegedly used in the failed assassination attempt against the Bulgarian dissident journalist Vladimir Kostov the same year in the Paris Métro. The poison used in both cases was ricin. Both assassination attempts are believed to have been organized by the Bulgarian Secret Service at the time of the Cold War, with the assistance of the KGB. In Breaking Bad, when Jesse and Walt plan to kill Tuco with ricin, Walt mentions the "Bulgarian Umbrella," as that was what delivered the ricin.
The caviar in the tin is a Beluga which is caviar consisting of the roe (or eggs) of the beluga sturgeon Huso huso. The fish is found primarily in the Caspian Sea, the world's largest salt-water lake, which is bordered by Iran, Azerbaijan, Kazakhstan, Russia, and Turkmenistan. Beluga caviar is the most expensive type of caviar, with market prices, at the beginning of the millennium, ranging from $7,000 to $10,000/kg ($3,200 to $4,500/lb).
When they are talking about Soviet submarines at the dinner party, they reference the K-19 & Akula classes. The K-19 was the name of a Hotel class, nuclear missile submarine that had a nuclear reactor problem & had to be towed back to port in 1961 to much publicity and shame in Moscow. The Akula was a class of fast attack submarines which did not carry nuclear missiles as was implied by the discussion. They could carry a few cruise missiles, however. Even if you put aside these discrepancies, the K-19 still had the ability to carry more warheads. Comparing both ships would be like comparing apples to oranges.