Alexandria's newly elected City Council and city officials met Saturday on a tree-shaded terrace at Mayor Charles E. Beatley's 300-acre Warrenton farm to get acquainted with the issues and each other--and to agree on what to disagree on.

Traditionally, such a meeting serves as the new council's chance to set its agenda and establish its priorities for the next three years. In 1979, the meeting lasted two days and was held at a city high school. Because most of the council was new, orientation was the name of the game.

This year, however, with only two newcomers on the six-member council, the entire meeting lasted six hours, under a red-and-white-striped awning, and aside from a concern about the slumping economy and the heat, much of the talk was as perennial as crab grass.

"There wasn't much we did that was specific," new council member Lionel Hope said after it was over. "But just seeing that long list of issues was bracing."

Some examples:

* The Economy: City Planning Director Engin Artemel reported that high interest rates and a slumping rental market are slowing expansion of the city's tax base. Office construction, which soared to $40 million in 1981, has fallen to $30 million this year. Housing starts also are down, and falling rental rates in the District mean suburban office space is harder to fill, he said.

The Democratic-dominated council was quick to trace those economic woes to the Republican administration across the Potomac and did not rule out increased taxes or cuts in social services if the economic picture does not brighten.

* The Waterfront: The city's long struggle with the federal government over who owns what on the Alexandria waterfront may be ending, but the Justice Department still is negotiating settlements with private landowners. Council members are worried that Justice's lawyers are ignoring density limits already agreed to by the city and the Interior Department. "Justice has reneged on its promise to abide by Interior's decisions," fumed one council member privately.

* Crime: "We've got people who pull a knife on a police officer, and they're back on the street the same day!" exclaimed Vice Mayor James Moran. That provoked similar reactions from other council members. But aside from agreeing that "we've got to do something," they made no specific proposals.

* Transportation: The council inspected and roundly criticized a consultant's proposal for a city bus system to shuttle residents and visitors to and from Metrorail stations. Beatley, who presided over much of the meeting with his customary taciturnity, was outspoken in support of the local bus system. "We're being sacrificed on the altar of Northern Virginia regionalism," Beatley warned. "We're going to fool around for 18 months trying to decide what kind of a bus system we want, and we're going to wind up buying Metrobus because they'll be the only ones in business."

That, Beatley argued, would be unfortunate. "You're never in control of your fares with Metro. Their buses are always going to be dirty and obsolete. We're going to be stuck like this forever, with other people's bus system problems, tied to a regional system that's going to down us."

The private bus system is a pet project of the mayor, and he has said he will make it a priority during his term. He said a local bus system is the only feasible way the city can save its downtown from massive traffic problems once Metrorail reaches Alexandria in late 1983.

* Refugees: City Manager Douglas Harman told the council that the city's federal funding for refugee care will be cut by about 20 percent this year, despite a rapidly increasing refugee population.

"This is a serious problem," Moran said. "It's getting worse, and it's not going to take care of itself. We've got people who are totally unprepared to cope with Western civilized life."

Moran told his colleagues of an admittedly extreme example: a family of Laotian refugees who built wood fires on top of their gas range in Alexandria because they had never seen a stove before.

The city planning office also marked the day by releasing detailed 1980 Census figures for the city. While Alexandria's overall population declined 7 percent between 1970 and 1980 (down to 103,217 from 110,938), the Landmark area on the city's West End grew by a whopping 138 percent. The area's population jumped from 5,686 to 13,566, while the older sections of the city lost residents by an average of 19 percent.

Blacks now make up 22 percent of the city's populaton, as opposed to 14 percent in 1970. Hispanics and Asians increased five times between 1970 and 1980, to 5,485. That percentage increase was more than the District's, but only half that of Arlington.

Beatley had promised to finish the meeting by 4 p.m. and he did. A picnic followed, and then a hike around the farm, led by a reputedly inexhaustible Beatley. "Chuck is something," council member Hope said. "He must have walked us two miles, and I don't think it fazed him." As for the rest of the crowd, "Well," Hope said, "we were hot and a few other things, too."