The Magna Group Inc., based in Kensington, has models under way at the Fairways at Leesburg Country Club, where 141 lots have been acquired for single houses that will be priced in the mid- $90s. The golf course site is one mile south of Leesburg. The colonial houses will have two-car garages and ceramic tile baths.

Land Development Associates Inc., based in Laurel, is planning construction of a second phase of its Amber Meadows professional building development on the Rte. 15 corridor near Frederick, Md. Nearby are a racquetball club and a skating center. LDA also is a co-developer with Ryan Homes in building detached houses and town houses at Amber Meadows.

Financing of $18.2 million has been arranged by Barnes, Morris & Pardoe Inc. for the 12-story office builing started at 1110 Vermont Ave. NW. The 294,000-square-foot building is expcted to be completed late in 1980.

The Department of Housing and Urban Development has announced that the maximum allowable interest charges for FHA-insured mobile-manufactured homes has been increased to 12 1/2 percent. A combination mobile home and lot loan now has a ceiling of 11 1/2 percent.

The acre-plus Wakefield Neighborhood Center has been dedicated at St. Charles, the new community in Charles County.

Orchard Hill, being developed by Lightpoint Associates, is a 29-acre parcel on Oakland Mills Road near Columbia, Md. L. Earl Armiger, a Howard County land planner, and FAM Funding Inc., are partners in the development to provide 118 home building sites.

Nuclear power will be the topic of speakers at a meeting of the Suburban Maryland Home Builders Association to be held May 31 at the Sheraton-Lanham Inn.

Long & Foster Real Estate Inc. has announced that it now has more than 1,000 licensed sales associates in its 30 area offices. Partner P. Wesley Foster recently bought out the interest of Henry A. Long in the 11-year-old firm.