People keep going and coming in trade associations related to housing and real estate. This week the legislative vice president of the National Association of Home Builders, Denis O'Toole, told the association he plans to move over to the American Bankers Association's legal staff - at a higher pay level. He will handle the ABA's growing interest in mortgage lending. A few weeks ago Dan Dobson left NAHB as vice president for conventions and meetings. His post is being filled temporarily by Charles P. McMahon, who had retired last fall as senior staff vice president.

Over at the Mortgage Bankers Association, where Mark P. Riedy succeeded Oliver H. Jones as top staff executive last fall, the word is out that John M. Wetmore will be leaving his chief economist's chair within a few months. One report has it that Wetmore could wind up next door at the Federal National Mortgage Association, where veteran chief economist Harry Schwartz is preparing to move into retirement this summer.

The National Association of Home Manufacturers, a smaller trade assocition also based here, has named John R. Kupferer executive vice president to replace Don L. Gilchrist, who resigned to develop a housing industry consulting practice. It was no secret that Gilchrist had policy difference with NAHM chairman of the board Walter E. Ekblaw, who is president of Toledo-based Scholz Homes, Inc. Kupferer had been serving NAHM as vice president for operations for two years.

In the private sector, John C. Lodge has joined Town & Country Properties, Inc., one of the largest real estate brokerage firms in the area, as director of marketing. He replaces Warren Elliott, who departed for the Southwest. Lodge had been promotion manager for Busch Gardens at Williamsburg, Va.

Although the deal has not yet gone to settlement, it is known that Holland & Lyons Associates, a firm that has been active in small condominium conversions and creations in the District, is planning to purchase the 48-unit, 12-year-old Berkeley House apartment building at 15th and P streets NW for conversion to ownership. The Franks S. Phillips realtor and mortgage banking firm owns the building, which reportedly will bring $900,000. Partner Robert Holland said that a meeting will be held next week with Berkeley tenants. He said they will be encouraged to buy the relatively small efficiency and one-bedroom apartments "as is" and with tenant discounts. Holland insisted that tenants uninterested in buying the units, which are expected to be priced at $29,500 and $45,000, will be given professional and financial aid in relocating.

Home sellers and buyers in Northern Virginia should be happy to learn that Gov. John N. Dalton has signed legislation that will require funds to be disbursed within three business days after a settlement is made in a realty transaction. The law, effective July 1, also provides penalties for failure to accomplish the disbursal of funds. "This has been an area of considerable concern for several years in Northern Virginia," said Aubrey Gaskins, a staff executive of the Northern Virginia Board of Realtors. "We were aware that dilatory tactics by some attorneys and representatives of lenders often resulted in funds not being made available to sellers for an average of seven days after a transaction. We had been pushing hard for a law to require what is called a 'wet settlement,' with immediate or early payments in cash. Some sellers were forced to wait as long a four weeks to get the money that should have been on the table at settlement. This law should do the job."

The 192-acre Plummer farm in Potomac has been sold to Cowan & Hodgkin, Inc., a firm that has been building big, expensive houses in Potomac. The Plummer farm runs west along River Road from Piney Meetinghouse Road to Saddleridge. Cowan-Hodgkin also purchased the 25 1/2-acre Mize estate two miles north of Potomac Village and directly across River Road from Tara, where the firm has been building. Partner Wes Hodgkin said that negotiations for the Plummer tract, long sought by many custom builders in Potomac, were hampered when owner George Plummer died suddenly. But the transaction was completed with the bank handling his estate. "Mr. Plummer left no heirs, so the money will be distributed to charities he supported," Hodgkin noted. Partner Chet Cown added that a mix of "classic colonials and subtle contemporaries will be built on the Plummer farm to produce an "eclectic community."

Redskin-Restonians Eddie Brown and Mark Moseley have joined Reston resident-builder Warren Katz to form KaSkins Development Co., which has an exclsive from Deck House, Inc., of Acton, Mass., to build that firm's pre-engineered houses in Reston. Both Brown and Moseley said they are determined to become involved in both construction and management."We approached Warren Katz because we were looking for something physical to do to keep in shape during the off-season," said Brown, whose reputation heretofore has been mainly for kick returns. "My father is a builder in Texas and Eddie's dad has worked in construction in Tennessee," added Moseley. One recently retired Redskin, Jerry Smith, has been working several years with his brothers and realtor Jack Foley in building new homes in suburban Maryland.