Moscow — Yuri Andropov, reputedly more agile and broad of intellect than any Soviet leader since Lenin, has been named Communist Party chief in what has begun as a rapid and orderly transition from the rule of Leonid Brezhnev.
That leaves at least two key questions:
* How quickly and effectively will the 68-year-old former head of the KGB security apparatus consolidate power? (A strong signal could come as early as next week at a scheduled regular meeting of the party Central Committee. It is conceivable further changes at the top party team could be announced there, amid signs that one veteran Politburo member is in disgrace and rumors that another, the oldest at 83, is either seriously ill or has passed on.)
* Will Mr. Andropov embark on a decisive departure from the gradualist approach that came to mark the 18-year rule of Mr. Brezhnev? Put differently, does being bright and not too dogmatic mean a new leader will necessarily approach the nation's relatively well set docket of unresolved problems much differently than did his predecessor?
(A signal on this score could also come at the Central Committee sitting, particularly since the session is theoretically supposed to deal with economic problems. Yet many Western and East European diplomats are assuming it will come considerably more slowly.)
One likely factor in the pace and success with which Mr. Andropov manages to become party leader in deed, not just in name, will be the future role of a politburo colleague named Konstantin Chernenko.
Mr. Chernenko, a close protege of the late Mr. Brezhnev, had long been tagged by foreign Kremlinologists as a top candidate for the job Mr. Andropov has won. And senior officials have told the Monitor that since late spring of this year - the real starting point for the transition ''process'' that has simply broken into the open with Mr. Brezhnev's passing - Mssrs. Andropov and Chernenko have in effect shared the bulk of the day-to-day running of the party.
In a show of political street smarts even the likes of former Chicago Mayor Richard Daley could have envied, Mr. Andropov and/or his backers arranged for Mr. Chernenko formally to nominate him as Communist Party leader at an extraordinary meeting of the party's full Central Committee Nov. 12. Soviet sources suggest the meeting was a brief, smooth ratification of the senior party leadership's pick of Mr. Andropov.
Still, Mr. Chernenko, the only listed speaker at the meeting besides the new party chief, did not talk like a man happy to stand in Mr. Andropov's widening shadow. Chernenko's speech was sprinkled with specific policy pointers. Chernenko also stressed the need for ''collective'' leadership, adding that this approach was''doubly, triply more important'' in light of Mr. Brezhnev's death.
Historically, the Soviet system has abhorred genuinely ''collective'' rule. Amid likely Kremlinological guesswork in the interim, only time will tell whether the initially smooth switch from Mr. Brezhnev's tenure means this historical pattern has changed.
What is apparent is that Mr. Andropov's selection as top party man may represent a significant shift from another historical pattern. After Lenin, the nation's first post-revolution leader, passed on in 1924, the more cerebral component of the Bolshevik party gave way to the political managers of which Joseph Stalin, Nikita Khrushchev, and Leonid Brezhnev were all, in their very different ways, examples.
Mr. Andropov - although said by sources who know him to be strong on political shrewdness - is also portrayed as far more the intellectual than his recent predecessors. Part of this image may well be the function of Soviet-Socialist public relations, and the qualities attributed to Mr. Andropov need not necessarily have major policy implications.
If the new party leader is likely to act like a Western ''liberal,'' as at least a few Western portraits imply, he has been hiding that side of his character expertly during his career as diplomat, senior party official, and, until this spring, longtime head of the KGB.
But there are some fairly good signs Mr. Andropov may prefer original thinking to reliance on dogmatic formula. One East European source here, for instance, says that it was Mr. Andropov, as ambassador to Hungary during the Soviet military intervention there in 1956, who convinced the party leadership in Moscow to draw up a conciliatory declaration of principles on international communist relations on the heels of the Hungarian uprising.
The declaration was the Soviet party's first known concession that all international communist parties were equal groups, with no single center of domination. It was on this platform, the source says, that Mr. Andropov was soon brought back to Moscow to head the department within the Central Committee Secretariat in charge of ties with Eastern Europe.
If one is to judge a man from the company he keeps, Mr. Andropov is doubly interesting. For among those said by senior officials to be closest to the new party leader are some of the Soviet policy machine's more articulate and less dogmatic specialists, as well as some early public theorists of Soviet detente with the West.