The Metro board voted yesterday to speed construction of two suburban Maryland rail lines while delaying a third. It also decided to add more passenger entrances at three stations and expand automobile parking at two others.

The decisions depend heavily on getting enough money to build all the planned 100-mile transit system. They provide for service from Silver Spring to Glenmont in Montgomery County by 1986, a year earlier than now scheduled, and from Anacostia to Rosecroft in Prince George's by 1987, a year later.

The board also revived an old idea of building a seven-mile line from Greenbelt in Prince George's to the existing Fort Totten station in Northeast Washington, and running shuttle trains until the inner part of the Greenblet line is built all the way downtown.

Prince George's passengers would transfer at Fort Totten to the existing Red Line to get downtown. Service would start in mid-1987, about six months earlier than now scheduled.

Changes approved yesterday will make no big change in the $3 billion needed to complete the system, half of which has been assured. Metro and local officials are looking to the federal government for a big part of the increase.

The board also voted officially to abandon Metro's high-vault ceiling design for all future subway stations except Navy Yard in Southeast Washington. Lower, less costly designs will be used.

The board approved these additions:

A second passenger entrance at the south end of the Friendship Heights station, for which financing is apparently available.

Future second entrances, depending upon financing, at the planned Columbia Heights station on upper 14th Street NW and the already overburdened Pentagon station. In addition, bus-transfer facilities would be added at Columbia Heights.

A 500-car parking structure at the Medical Center station and a 1,500-car parking structure at Grosvenor station, both in north Bethesda. Old plans call for 500 spaces at Grosvenor and none at Medical Center. Special federal financing from highway funds is probably available.

A bus-only ramp from the planned West Falls Church station to a proposed extension of the Dulles Airport access road in Fairfax County.

More bus passenger shelters at Silver Spring.

Board members agreed to consider one last round of name changes for existing and future subway stations, although some were jolted by the $400,000 estimated cost just for buying new destination signs for Metro cars.

One proposal would change the name of the Stadium-Armory station to Starplex-Hosp, reflecting the District of Columbia's official designation for the Stadium/Armory complex and its proximity to D.C. General Hospital. Space would require the abbreviation.

"A plastic application," director Joseph Alexander said, wincing at the mention of Starplex. "I don't think it should be encouraged," added chairman Joseph S. Wholey.

Among other official suggestions for name changes are: Nicholson Lane to White Flint, Addison Road to Seat Pleasant, Georgia Avenue to Petworth, Chillum to West Hyattsville and Alabama Avenue to Congress Heights. Francis B. Francois, a Prince George's director floated the idea of renaming New Carrollton, on the recently opened Orange Line, as Beltway East.