You're asking for information about people and organizations whose entire existence revolves around secrecy, so there will likely be a lot of hand-waving.
But there are some interesting sources of information about what spies do: former spies who write spy novels that are supposedly entirely fictional but later turn out to be based, in some part, on real events and people.
James Bond was written by Ian Fleming, who actually did some (few, and highly-embellished) things that show up in his books. Fleming, code-named 17F, was a Commander in the Naval Intelligence Division; James Bond, code-named 007, was (officially) a Commander in the Naval Reserve Division. Fleming authored Operation Goldeneye, which would maintain a resistance network in Spain if it fell to the Germans. He was the intelligence director for 'Operation Overlord', the British code-name for the Normandy invasions. He created a unit of specialist intelligence commandos - "trained in unarmed combat, safe-cracking, and lockpicking" - who would sneak into enemy bases and steal documents.
The 'spies on a train' thing in 'From Russia With Love' was based on true events:
The novel's plot device of spies on the Orient Express was based on the story of Eugene Karp, a US naval attaché and intelligence agent based in Budapest who took the Orient Express from Budapest to Paris in February 1950, carrying papers about blown US spy networks in the Eastern Bloc. Soviet assassins already on the train drugged the conductor, and Karp's body was found shortly afterwards in a railway tunnel south of Salzburg.
Fleming mined these real people and events, taking the most interesting bits of each, to create James Bond:
Fleming based his fictional creation on a number of individuals he came across during his time in the Naval Intelligence Division during World War II, admitting that Bond "was a compound of all the secret agents and commando types I met during the war".
Fleming was showing the humility expected of an English gentleman, as well as not violating any number of secrecy oaths and Acts, by carefully not mention how, where, or why he met such people. One of them was his brother Peter, who was an 'adventurer' and a spy engaged in "military deception". I mean... just look at the guy, that's half of James Bond right there.
John le Carré was a spy with MI5 and MI6 (the Secret Intelligence Service) engaged in counter-espionage with the Soviets. His spy career was ended when someone outed him to the KGB; that someone later turned out to be Kim Philby, one of the Cambridge Five, who were KGB moles in the upper reaches of British Intelligence. The book (and excellent movie) 'Tinker Tailor Soldier Spy' is a montage of real and fictional events but has been praised by people who were there for its fair characterization and lack of sensationalism.
E. Howard Hunt, CIA agent and Watergate spook, wrote a bunch of spy books (under his name, and a few pseudonyms) that were similarly informed by his own experiences.
War is war, unconventional shit happens. Ian Fleming experienced this, and James Bond was informed by those experiences. But Fleming was skimming the cream off the top... decades of intelligence work by hundreds of spies, including some crazy things that could only have happened during a World War, were condensed into one character. Real spies today probably detest James Bond, as they sit behind their desks combing through data and shuffling secrets around.
The Cold War was like a chess game. John le Carré experienced this, and his books were informed by those experiences. Grey men fighting a grey war that even they didn't really care about anymore.
E. Howard Hunt threw it all away for Nixon, so... a little less grandeur there.