October 21, 1984

Call Whoopi Goldberg a comedienne and she shakes her head so vehemently that her pixie-like face almost disappears under an umbrella of tiny corkscrew braids. Call her an actress and she laughs because, she says, the image that comes to mind is ''like tweaking a cheek,'' and she is not a person who would stand for cheek- tweaking. No, she says emphatically, she is not an actress. Well, Whoopi, what are you? ''I'm an actor,'' she says, without hesitation.

The Reagan Administration decided today to reduce significantly the size of the United States Embassy staff in Beirut as a result of continuing security threats, State Department officials said. One official said the move would reduce the number of official American personnel to about 30, from 45 on Friday. The embassy staff on Sept. 20, when the substitute embassy building near East Beirut was bombed and two Americans were killed, included 99 Americans. Total Was 190 in 1983 Officials also noted that on April 18, 1983, when the original American Embassy building in West Beirut was destroyed by a car bomb, there were 190 United States personnel there. But at that time the United States was actively involved in all facets of Lebanese life, supplying the Lebanese Army with military equipment and advisers, undertaking a large-scale aid program and trying to bring stability to Lebanon's political life.

When the historic breakup of the American Telephone and Telegraph Company was announced in January 1982, executives at scores of telecommunications companies were certain that a huge, lucrative market had been laid at their feet. ''It's what we've been pushing for for a long time,'' William G. McGowan, chairman of the MCI Communications Corporation, said the day he heard the news. Mr. McGowan probably winces when he remembers those words now. On Monday, MCI reported a plunge in quarterly profits from 1983. In addition, its third- quarter revenues actually dropped from the prior three months. Its main source of comfort is that none of its competitors - including A.T.& T. itself - is doing any better. The year 1 A.D. (after divestiture) has proved a bonanza of sorts for consumers, who have seen prices for long-distance phone service and telephone equipment plummet as myriad companies battle for their business. But it has been a brutal year for MCI, ITT, GTE-Sprint, and other contenders for shares of what had once been the domain of A.T.& T. For them the Jan. 1 breakup of the old phone monolith has brought price wars, management shake-ups, foreign competition, depressed profits - even red ink in some cases - and plunging stock prices.

Government officials said today that senior American military officers had begun to move more freely around El Salvador. But they denied there had been any changes in rules barring advisers from combat. Questions about their role arose Friday after three advisers assigned to the United States Embassy were seen near Perquin, near the site of a battle between Government soldiers and rebel troops. American diplomats in San Salvador said the rules governing adviser activities appeared to have become more flexible.

LAST summer, Democratic strategists targeted foreign affairs as President Reagan's most vulnerable area and laid plans for a campaign building to a foreign- policy crescendo in late October. Even in September, when Walter F. Mondale was floundering, his aides resisted turning from deficits and taxes to foreign policy. ''The time for that is October,'' one of them firmly insisted. Deliberately, the Mondale camp fought for and won agreement for what has become a make-or-break event, the second Presidential debate, on foreign policy, in Kansas City tonight. In that sense, the political script has followed the Mondale scenario, though 16 days before the election the former Vice President lags farther behind than his lieutenants wanted. But the Democratic nominee has pulled up from still farther back. Yesterday's New York Times/CBS News Poll put President Reagan 13 points ahead. The week before the first Presidential debate, on domestic policy issues, he led by 23 points.