The Democratic National Committee panel amending presidential-nomination rules approved a mixed bag of minor changes yesterday permitting Wisconsin to return to its open primary; assuring Iowa and New Hampshire their place at the start of the nomination season; lowering barriers to long-shot candidates in some states and increasing the advantages for front-runners in others, and providing for a slight increase in the number of elected officials and party leaders at future conventions.

The changes "leave the process in 1988 looking pretty much like the one we had in 1984," said Donald L. Fowler, chairman of the party's Fairness Commission.

Yesterday's decisions -- in their substance and swift approval, and the absence of acrimony -- represented a vote of confidence for party chairman Paul G. Kirk Jr., who prevailed both on the adjustments he sought and on his if-it-ain't-broke-don't-fix-it posture toward more comprehensive change.

The tidiness of the session was such that Fowler was moved to exclaim, "Well, who would have believed it!" as the 51-member panel needed just seven hours to dispose of matters it had set aside four days to address.

Fowler attributed the ease of the process to the fact that "we got started early and didn't give the candidate-driven pressures of 1988 a chance to develop."

Representatives of Democratic Sens. Edward M. Kennedy (Mass.) and Gary Hart (Colo.) monitored the session but did not try to influence votes.

They later proclaimed themselves satisfied with the panel's work.

The commission will meet next month to draft specific language before presenting its report to the DNC for all-but-certain approval. But the basic outline of its work is now in place.

It includes:

*A 23-to-7 vote to allow Wisconsin to return to an open presidential primary, in which independents and Republicans may participate along with Democrats. A delighted Gov. Anthony S. Earl (D) said the vote was "like removing an abscess." Last year the DNC forced Wisconsin to select delegates in a closed caucus, contrary to its political tradition. While the new rules accommodate the open-primary heritage of states such as Wisconsin and Montana, they do not allow other states to switch to an open primary.

*A calendar that preserves the early-March-to-early-June "window" of primaries and caucuses, with the four exemptions allowed in 1984: Iowa can go 22 days before the "window"; New Hampshire 14 days before; Maine 10 days before, and Wyoming three days before.

*A lowering of thresholds from 20 to 15 percent in all caucus and some primary states, addressing the complaint of Rev. Jesse L. Jackson that his supporters were "betrayed" in 1984 because their votes, if they did not add up to 20 percent in a state, yielded no delegates. At the same time, the panel moved in the opposite direction by preserving and even strengthening various "winner-take-more" schemes in the 1984 rules.

*A provision that 80 percent of Democratic senators and House members will be automatic, unpledged delegates to the party's convention -- up from 60 percent in 1984 -- and a provision that they be selected at the end of April, rather than January, as they were last year.

*A provision that all 372 DNC members be automatic, unpledged delegates. This raises the number of slots set aside for party leaders and elected officials to 1,046, 26.6 percent of the convention delegates in 1988, up from 22 percent in 1984.