Former President Jimmy Carter is back in the spotlight in concert with his book ''Keeping Faith,'' which was released for sale Oct. 15. The 622-page book is dominated by discussion of the Mideast peace talks and the Iranian hostage crisis, topics on which Carter has recently, and publicly, commented. On ABC's ''20-20'' last week, Carter said:
* He would have ordered an attack on Tehran if one of the 53 Americans hostages had been injured or killed.
* Israeli Prime Minister Menachem Begin is ''intransigent and stubborn'' but also holds his ''great admiration and respect.
* He was disconcerted after a briefing with Ronald Reagan, two days before Reagan took office, when the President-elect seemed disinterested, failed to ask questions, and didn't take any notes.
In addition, the Boston Globe published an off-the-record interview with Carter made in January 1981. In it, Carter criticized three former secretaries of state: Alexander M. Haig as too political; Cyrus Vance as too ''reticent;'' and Henry Kissinger as ''brilliant but devious.''
In his memoirs, Carter barely masks his scorn for what he sees as lack of inertia in Congress and the State Department, but during the Globe interview he told reporters the State Department ''had not produced a new idea in 20 years.''