President Reagan, pulling out all the stops to win the tax fight, took his heavily sugared tax bill to Capitol Hill personally yesterday and announced plans to go on national television Monday night to present the package t the public.

Reagan disclosed to Congress full details of well over $30 billion in new sweetteners, including income tax indexing to counter inflation and tax breaks for commodity dealers.

The "revised" administration proposal includes at least two provisions strongly opposed by the Treasury Department in the past, and would back a Senate-approved restructuring of the personal income tax system to create what amounts to permanent cuts every year starting in 1985.

"It reads like a French novel," said Rep. Barber B. Conable Jr. (N.Y.), ranking Republican on the Ways and Means Committee and the GOP bill's principal co-sponsor.

While saying he was satisfied with the product, Conable appeared uneasy about the sweeteners, particularly those for the oil industry, noting that "It's awfully easy to focus on the add-ons . . . . If I were writing this bill, I would write it differently. Everybody would write it differently."

It was not at all clear yesterday whether the additions would be adequate to pull enough southern Democrats in the House out of the party fold to assure passage.

Various sources said that at least four of the nine Texas Democrats who defected to Reagan in the last budget vote are committed to the Democratic leadership, along with at least two Louisiana Democrats who had backed Reagan in earlier votes.

In a related development, one undecided member of the House, Rep. Stephen L. Neal (D-N.C.), complained that he had received a letter from the National Conservative Political Action Committee (NCPAC) in suport of the president's bill, and that the letter amounted to a bribe offer.

"If you will make a public statement in support of the president's tax cut and state that you intend to vote for it, we will withdraw all radio and newspaper ads planned in your district. In addition, we will be glad to run radio and newspaper ads applauding you for your vote," the conservative group wrote to Neal in a letter signed by John T. (Terry) Dolan, the chairman.

Dolan countered: "Everyone has a right to go to a congressman and say if you don't vote a certain way, I'm going to oppose you."

On another front, liberal Democrats discontented with both the Democratic-controlled Ways and Means Committee's tax bill and the GOP tax cut began to emerge. Two, Reps. Morris K. Udall (Arix.) and David R. Obey (Wis.), announced plans to sponsor, on the floor a one-year tax cut. r

"This Christmas-tree game has gotten out of hand," Udall said, referring to the bidding war for southern conservative votes that has produced the host of special interest amendments in the GOP and Democratic bills.

"It would probably be cheaper if we gave everybody in the country three wishes," Obey added. At least 10 Democratic liberals are expected to oppose the Republican substitute bill, but vote against the Democratic bill for final passage, if it survives.

In his personal appearance before the House Republican Caucus in behalf of his legislation, which he is to present to the nation in a prime-time television address at 8 p.m. Monday, Reagan sharply attacked the Democratic bill.In a series of one-liners, he said the Democratic tax cut gives more to the American worker "if you only planon living for two years."

Among the major new additions to the Reagan bill, which faces a key fight in the House Wednesday:

Retention of a tax loophole for commodity dealers that could cost the Treasury about $400 million in 1982. On July 14, the president had attacked Democrats for maintaining exactly the same loophole, declaring that Democrats "have gone out of their way to offer 2,500 commodity specualtors a tax break of $400 million." Yesterday, Treasury Secretary Donald T. Regan justified the reversal of policy on the grounds that it will help achieve the "greater good" of passing the president's tax bill.

Indexation of tax brackets, the $1,000 personal exemption and the standard deduction or zero bracket amount to the consumer price index starting in 1985, at the end of three years of across-the-board rate cuts totaling 25 percent.

A halving of the time an asset must be held to qualify for capital gains tax rates instread of ordinary income tax rates. Under current law, the asset must be held one year; the administration proposes changing that to six months. m

Tax braks for the oil industry that would amount ot just over $13 billion over five years, according to Treasury estimates, and to more than $16 billion, according to estimates by the Joint Committee on Taxation.

A tax exemption of up to $2,000 for joint returns on income from special certificates to be issued by lending institutions between Sept. 30, 1981, and Dec. 31, 1982. The administration has strongly opposed these provisions, which are backed by the savings and loan lobby.

The $400 exemption for interest income on joint returns would be ended and replaced with a mechanism for exempting 15 percent of interest income in a system that would require a taxpayer to have a much larger amount of money earning interest in order to qualify for a $400 exemption.

The administration bill accepts the attempt to end the marriage "penalty" in the same way as the Senate tax bill, would expand the use of individual retirement accounts paralleling both the Senate measure and the Democratic bill and calls for the near-elimination of the estate tax, along the same lines as the Democratic bill.