Eva Estrada Kalaw, a prominent veteran of opposition politics in the Philippines, was approached yesterday for advice by college students who were planning a street demonstration to protest the slaying of their idol, Benigno Aquino Jr.

She advised them to cool it. "I told them," she recalled today, "that they would only pour out their anger and then sit on their laurels."

That might be judged strange advice from a woman who has made a reputation by pouring out her anger against the government of President Ferdinand Marcos. Kalaw, a former senator who is now vice chairman of the 12-member opposition coalition known as the United Nationalist Democratic Organization, is a bitter critic of the president.

But her calming advice to the students reflects the opposition's judgment that Aquino's assassination should not be used to incite radical actions.

Opposition leaders have blamed the government for not protecting Aquino when he was gunned down Sunday at Manila's airport as he returned from three years of self-imposed exile in the United States. They have demanded that Marcos provide answers to several questions on the killing, yet they have refrained from incendiary statements that might provoke violence.

This formal reticence partly explains the absence of serious trouble here during the past two days. Minor demonstrations have been held on some campuses, but there have been no large, violent outpourings of emotions. A large crowd that had gathered at the airport Sunday to welcome Aquino disbanded in shock when informed of the shooting, but no one so much as threw a rock.

The only large gathering has been the seemingly endless line of Aquino's followers who file silently through his modest home in suburban Quezon City to view the body of their martyr. Thousands waited in sporadic rainstorms today to glimpse his remains.

Aquino's wife, Corazon, and her five children left their home near Boston Tuesday to fly to Manila to arrange for funeral services Sunday, The Associated Press reported. They will arrive Wednesday.

The slain opposition leader's younger brother, Agapito, standing on a platform, told the hundreds of mourners gathered at the family home outside Manila that a "massive procession" was planned for Thursday, when the body will be moved to a nearby church.

The family said 50,000 mourners have viewed the body since it was put on display Monday morning.

Meanwhile, the government announced its first clue in the search for the identity of the lone gunman officials say killed Aquino. The official Philippine News Agency quoted Gen. Prospero Oliva, the Manila police chief who is heading the investigation of the slaying, as saying that the gunman, who was killed by security officials at the airport, had the nickname Rolly embroidered on his underwear. That matched the "R" engraved on a ring he was wearing, Oliva added. However, his identity is still unknown, officials said.

Rolly is a nickname common among Filipinos named Roland.

Seated quietly on a patio a few yards from the coffin, Kalaw explained that the opposition coalition favors reconciliation, not confrontation.

"The position is for reconciliation," she said, "although I personally favor reconciling only with a decent sector of the government." This means, she said, dealing not with Marcos but perhaps with Prime Minister Cesar E. A. Virata.

"Marcos is a sick man, and the economy is so bad that his credibility is zero," she added.

Marcos had been in seclusion for several days before his television appearance last night, ostensibly writing a book. This and other recent periods when he had not been seen had fanned persistent rumors that he is seriously ill, but he disputed that last night, and the Philippine Embassy in Washington issued a statement last week saying it was not true.

Kalaw said the purpose of a dialogue with the government would be to reach an agreement for holding "free elections" for the National Assembly next year. Like most members of the opposition here, Kalaw is convinced that Marcos' forces would be defeated in an election that was run fairly. Past elections in this country have been accompanied by accusations of massive vote fraud arranged by the government.

The opposition coalition had counted heavily on Aquino's safe return to Manila as a galvanizing force in elections next year. Even if he had been jailed, as most expected he would be, his name would have been used to unite the often disharmonious opposition groups under one banner. A charismatic man with a broad appeal, Aquino, had he lived, would have been a powerful force here.

His slaying has left a big gap in the opposition's ranks. Several others of prominence have left the country for exile in the United States.

No replacement is in sight. Some in the opposition coalition have suggested that Agapito Aquino should be anointed as his brother's successor. Agapito, widely known by his nickname Butz, is a successful manufacturer of plastic chairs but never shared Benigno's political prominence.

There is no indication that Marcos wants any part of a dialogue with his opponents, and his statements during a television news conference last night did not seem likely to encourage reconciliation.

Marcos accused his opponents of fomenting hatred against his administration by "orchestrating" the many rumors that swept through the city yesterday, one of which was that he is a sick and dying man. Marcos has expressed deep sorrow at Aquino's death but has extended no olive branches to the opposition leaders.

The first test of the opposition coalition's "reconciliation" policy is likely to come rather quickly over the question of an official investigation of Aquino's assassination.

Kalaw said today that the coalition wants the investigating body to be composed of government figures and representatives chosen by the Aquino family. Marcos has given no hints about the choice of investigators.