President-elect Ronald Reagan arrived in Washington last night, his first visit to the nation's capital since his landslide victory over President Carter two weeks ago.

Before returning to California on Friday, Reagan is to meet with Carter at the White House, receive briefings from the Central Intelligence Agency and confer with congressional leaders. The president-elect went straight from Andrews Air Force Base last night to the townhouse on Jackson Place NW that will be his Washington home until he moves across Pennsylvania Avenue into the White House.

He arrived to find Washington awash in rainwater and rumors about who will fill Cabinet and other key posts in his administration. Yesterday, speculation centered on the Pentagon, with Sen. John G. Tower (R-Tex.) emerging as a front-runner to become secretary of defense.

Reagan's week here will be divided between ceremony and substance.

Today he will have separate half-hour sessions with the House and Senate Republican leadership, and will drop in on the Democratic leaders of the two houses. He is to stop off at the headquarters of the Teamsters union, one of the handful of labor organizations to endorse his candidacy, for a half-hour talk with the union's executive committee. Tonight the president-elect and Nancy Reagan are to host a dinner at the F Street Club in Foggy Bottom.

After a CIA briefing Wednesday morning, Reagan, escorted by longtime friend Sen. Paul Laxalt (R-Nev.), will lunch on Capitol Hill with Republican members of Congress. That night the Reagans will dine with GOP senators and their spouses at the Dirksen Senate Office Building.

Thursday morning there will be further intelligence briefings. In the afternoon the Reagans will visit with the Carters. According to the official schedule, Rosalynn Carter is to give Nancy Reagan a tour of the White House while their husbands talk. Thursday evening the Reagans will have dinner at the Chevy Chase home of columnist George Will.

Friday morning the president-elect will visit his transition headquarters on M Street NW, and then the Reagans will return to Los Angeles. There Reagan probably will meet with his "kitchen cabinet," the group of longtime friends who are reviewing possible nominees for Cabinet posts.

Edwin Meese, Reagan's senior aide who has been named to be White House counsel with Cabinet rank, told reporters on the Reagan plane en route to Washington yesterday that names of prospective Cabinet members will be presented to the president-elect within 10 days. Meese said the process of drawing up short lists of prospective nominees was proceeding on schedule.

Meese also said that Reagan and his Senate allies may attempt to block some of the appropriations bills in the current, lame-duck session of Congress. Meese said the object would be to block new spending levels in the Carter budget "so we can take a full look at the appropriations bills in the next session," when Reagan is in the White House and the Republicans control the Senate.

Reagan's transition office announced several new appointments yesterday, including Paul J. Manafort, 31, to be personnel coordinator in the key transition office headed by William E. Timmons.

Manafort was associate director of the Presidential Personnel Office from 1975 to 1977 under President Ford. He coordinated convention states for Reagan in the primary election campaign and was political coordinator for the southern states, where Reagan shattered President Carter's base.

Manafort is a partner of Charles Black in a political consulting firm. Black left the Reagan campaign in the purge that removed campaign manager John Sears last winter. Asked how that affected him, Manafort said: "I survived." His other partner, Roger Stone, will be given a transition post soon, Manafort said.

In 1976, Manafort was involved in the personnel side of a presidential transition, representing the outgoing Ford administration.

Other posts filled yesterday:

Office of Special Trade Representative -- Henry Berliner, a lawyer long active in District Republican politics. He led the D.C. delegation to the 1972 and 1976 GOP conventions, and was active in the Reagan campaign.

International Trade Commission -- Michael A. Samuels, former ambassador to Sierra Leone and currently executive director for Third World Studies at the Georgetown University Center for Strategic and International Studies.

Federal Emergency Management Agency -- Robert H. Kupperman, who for six years in the late 1960s was in the President's Office of Emergency Preparedness, predecessor of FEMA. He is coauthor of "Terrorism: Threat, Reality, Response," and has long been interested in the management of crises, both natural and manmade. He was chief scientist of the Arms Control and Disarmament Agency from 1973 to 1979 before becoming a senior fellow at the Center for Strategic and International Studies.

Administrative Conference of the United States -- Robert J. D'Agostino, national chairman of Law Deans for Reagan-Bush. He is associate dean of the Delaware Law School.

Advisory Council on Historic Preservation -- Sheila Rabb Weidenfeld, former press secretary to Betty Ford. She is a member of the President's Advisory Council on Historic Preservation and a trustee of the Wolf Trap Foundation.

National Aeronautics and Space Administration -- George Low, president of Rensselaer Polytechnic Institute in Troy, N.Y., and NASA's acting administrator under Presidents Nixon and Ford.

Corporation for Public Broadcasting -- Fran Griffin, a former talk-show host in Chicago who has been active in conservative politics in Illinois and Washington. She was press spokesman for the American Conservative Union and she recently set up her own public relations firm here.

National Endowment for the Arts -- Robert S. Carter, a Washington public relations man who was a presidential arts adviser under recent Republican administrations. A leader of the tiny D.C. Republican Party, he led the unsuccessful effort to have the local GOP come out against a proposal to give local residents voting representation in Congress.

National Endowment for the Humanities -- Richard J. Bishirjian, a political scientist at the College of New Rochelle in New York.