Should taxpayers foot the bill for the $35 former president Richard Nixon spent last year on parts for his electric golf carts?

Why does ex-president Gerald Ford need $2,242 in federal funds for plants and another $50 a month to water them?

These and other arresting questions about the subsidized life-styles of former chief executives were probed gently yesterday by a Senate Governmental Affairs subcommittee.

When it was over, the inquiring senators, Democrat David Pryor of Arkansas and Republican Ted Stevens of Alaska, appeared to agree that ex-presidents are not free-loaders but the law covering office expenses they can charge the government is "ambiguous." The legislators indicated they will try to remove the fuzz.

Both senators, moreover, indicated they are less than happy with the U.S. News and World Report article last month that detailed how the two ex-presidents spent $461,014 between them to maintain their offices. Stevens, particularly, sniffed at stories that "degrade" the presidency.

Most of the morning's testimony came from Raymond A. Fontaine, deputy controller of the General Services Administration, an outfit with first-hand knowledge of dubious outlays at the public expense. Repeatedly, Fontaine's budget director, William B. Early, explained that GSA had relied "on a judgment call" to approve ex-presidential spending. Both Nixon and Ford are passionate football fans and might have enjoyed the gridiron mataphor - as well as the fact that the calls invariably went their way.

The GSA team, taking their cue from the senators, were quick to point out that neither Nixon nor Ford put in for daily expenses while away from home base. They could have.

Nixon, moreover, never billed the United States for his trip to China in 1976 nor for his journeys to France and Britain last year, GSA affirmed, implying that nothing could have been more legitimate.

Allen R. Voss, director of the general government division of the General accounting Office, an agency with an altogether more gimlet-eyed reputation than GSA, supported his fellow bureaucrats. GAO is auditing the Ford and Nixon office spending for the past three years and has nearly finished the task. Voss told a reporter that his auditors had not yet found a single improper expenditure. However, the accountant in him was troubled over whether a few Ford items, like trips taken to back the Panama Canal treaties, should have been charged to the White House.

The law equipping ex-presidents with federally-supported offices lays down few standards. It does limit its beneficiaries to $96,000 a year for staff. It does provide for a "suitable" office, nonpolitical postage, and, under a 1969 amendment, travel outlays for the former president and two aides. But the law does not fix dollar limits, purpose or much else.

So, yes, Nixon did get 460,000 sheets of writing paper and 260,000 envelopes at a cost of $45,461. But his mail bag boasted two million letters after he was driven from office.

Yes, Ford did spend $23,485 on long-distance calls - "that's a lot of talking on the telephone," Pryor observed - but Ford's Palm Springs office is a long way from a switchboard. And anyway, Ford is now putting in a WATS line that will be cheaper.

Nixon's golf carts? An unfortunate misnomer. GSA calls them "electric carts." The government owns them and they are used to transport Nixon around his San Clemente compound and home. GSA does wish, however, that Nixon wouldn't pose in them with golf clubs.