The idea of establishing a national "art bank" to lease or lend works of art for maximum exposure in public places at least has reached a "starting point."

That was the phrase used yesterday by Sen. Harrison A. Williams Jr. (D-N.J.), sponsor of the national art bank bill, after hearing testimony marked by both enthusiasm and reservations.

If all the witnesses thought it might be a worthy idea, they also raised questions: costs of administration; how the art will be selected and distributed; whether artists should have the right of repurchase and at what price; the danger of politicization, and whether geographical quotas can be imposed on art.

Sen. Jacob Javits (R-N.Y.) said the hearings were to help the Senate Committee on Human Resources "map the reefs and shoals" of such legislation. And Williams, seeking advice from the founder of Canada's pioneer art bank, asked for help on "sticky wickets."

Suzanne Rivard Le Moyne, who founded and headed the Canadian art bank in 1972, said the bill's allotment of $250,000 a year for administrative costs is "totally unrealistic" and that revenues from rental fees and public auctions should not be overestimated.

She also felt that such terms as "support," "assist" and "help" are condescending in what is a two-way selling contract between the artist and the government.

The bill introduced by Williams would allot $9 million over three years, beginning with $2 million for fiscal 1979, for the federal government to purchase works of art. These would be available on loan to federal agencies or museums or could be leased to state or local governments, non-profit institutions or private corporations. Periodically, a public auction would be held to sell selected works.

The main idea is to make the art more accessible to the public for understanding and appreciation. The fringe benefits would include beautifying public places and making a new market for contemporary artists.

In Canada, start-up funds for a Canadian art bank amounted to a million-dollar-a-year allotment of five years, Le Moyne told the committee. In Canada, the works of art are leased for a 12 percent fee based on value. Even government agencies have to pay this fee, and they decide whether to use their furnishings budget for "thinner carpets or art or the reverse," Le Moyne observed.

The National Endowment for the Arts, which would take the art bank under its aegis in the bill, advised caution yesterday until a study is made on the impact on artist-dealer relationships, competition with museums and private collectors and full range of costs.

Mary Ann Tighe, deputy chairman for programs for the arts endowment, pointed out that the President's Task Force on Cultural Policy is studying the idea of an art bank while preparing an "issue-definition memorandum on American cultural life."