For nearly a week, little in Washington escaped their notice. Mikhail and Raisa Gorbachev's Soviet advance team, notebooks in hand, took in the monuments, museums and other landmarks. You might not have been able to tell them from a flock of fascinated American tourists if they hadn't been scribbling down everything they heard and saw.

At the White House, Chief Usher Gary Walters took the team on a "walk-through," that now-standard preview tour given all foreign advance teams preparing for official visits by their kings, presidents or potentates.

Walters, thorough and experienced in such things, told the Soviets what the Gorbachevs could expect to happen Dec. 8, from the Reagans' ceremonial greetings on the South Lawn straight through to the dinner that night.

The Soviets had a few questions: How many people would be invited to dinner? How long were the after-dinner toasts? What would the entertainment be? How long would it last? Did anybody accompany reporters during the mix-and-mingle in the Blue Room?

Led by V.T. Chernishev, the Soviets' urbane and sophisticated chief of protocol, the team's 14 members went away with their own copies of the White House guidebooks, including four-volume sets in leather-bound cases for each of the Gorbachevs.

They may want to take a look at those guides ahead of time. One room that wasn't on the tour is the Yellow Oval Room, upstairs in the family quarters. That's where the Reagans routinely chat with state guests in private for a few minutes before descending the Grand Staircase to join their other guests, and if the Gorbachevs want a sneak peek, they'll have to look in the guides.

The rest of the Gorbachevs' social schedule is less certain, since the Soviets haven't signed off on it yet, and that's causing another worry at the White House: when to have the traditional Christmas tree arrival ceremony.

The tree had been scheduled to arrive at 11 a.m. Dec. 9, but officials aren't certain yet whether Mrs. Reagan will be on hand to receive it, or involved with the Gorbachevs at that time.

"With or without Mrs. Reagan, it has to arrive no later than Thursday {Dec. 10} because otherwise there won't be time to decorate it over the weekend," said Elaine Crispen, Mrs. Reagan's press secretary.

The tree's press preview is set for Dec. 14.

"Henry, why don't you be a chef?" Henry Haller quotes his father asking him at age 14 back in Altdorf, Switzerland. "You can travel all over the world. And you will never have to worry about a job. People everywhere have to eat."

People sure do. For two decades, working for five American presidents when he was executive chef at the White House, Haller cooked for everybody who was anybody and a few nobodies as well. In fact, for 22 years there was hardly a world leader Haller hadn't fed.

Haller left the kitchen at 1600 Pennsylvania Ave. this fall, trading in his mixing bowl for a typewriter, so to speak. The resulting concoction, what Random House cutely calls "a dash of reminiscence and a pinch of history," is titled "The White House Family Cookbook" and is due in bookstores later this month.

Meanwhile, Haller's peers are feting him like the VIP he's become. A couple of weeks ago, they paid tribute to him with a dinner at the French Embassy. Tonight it's the Swiss Embassy where Chef Josef Tschigg is cooking up the honors.

Appropriately, Swiss Ambassador Klaus Jacobi and his wife Johanna are hosting the dinner, although Haller, who arrived in the United States in 1953, became an American citizen some years ago. Among the Jacobis' 34 guests tonight will be White House Pastry Chef Roland Mesnier, the Homestead's Executive Chef Albert Schnarwiler, the Mayflower Hotel's retired executive chef Bernard Binon, l'Auberge Chez Francois' Chef Francois Hearinger and Tivoli's Klaus Helmin. Also from the White House will be Curator Rex Scouten and Mai~tre d' Ho~tel Wilson Jerman.

The FBI may have overlooked the pot factor in Judge Douglas Ginsburg's past, but another Douglas with a Supreme Court connection -- the late associate justice William O. Douglas -- once believed the FBI was planting pot to trap him.

In the new book "Douglas Letters," edited by Melvin I. Urofsky, a professor of history at Virginia Commonwealth University in Richmond, and published by Adler & Adler of Bethesda, a letter Douglas wrote to two Washington State neighbors reveals his suspicions that the Nixon administration was out to oust him from the court.

In the letter dated May 12, 1970, and addressed to Kay Kershaw and Isabelle Lynn, Douglas writes:

"I wrote you last fall or winter that federal agents were in Yakima and Goose Prairie looking me over at Goose Prairie. I thought they were merely counting fence posts.

"But I learned in New York City yesterday that they were planting marijuana with the prospect of a nice big TV-covered raid in July or August.

"I forgot to tell you that this gang in power is not in search of truth. They are 'search and destroy' people.

"I do not know what the marijuana plant -- growing or dried -- looks like. I do not know if it would grow in Goose Prairie's harsh climate. Mint, white clover, and rhubarb do well there, as you know. But now that the snow is gone and summer is near, you might look to see if you can spot any marijuana. It would be ironic if they planted it in Ira's yard, not mine!"

Yesterday, an FBI spokeswoman called the idea pretty "far-fetched.

"Official FBI agents do not plant marijuana," she said. "Quite the opposite."

President Reagan gets his turkey -- a 55-pound Broadbreasted White -- on Monday when it and Herman Mason of Hinton, Va., president of the National Turkey Federation, go to the White House for the 40th annual Thanksgiving presentation ceremony.

This is no nameless bird, either. Known to intimates as Hawaiian Charlie, it was named for the 50th anniversary convention of the National Turkey Federation held last January in Hawaii and also for the federation's first president, Charles Wampler.

Friedrich Hoess, Austria's ambassador- designate, will hit the ground running when he arrives Sunday from Vienna. He'll go directly from the airport to the Cosmos Club, where the American-Austrian Society is tossing a champagne reception for him and his wife Claire.