* German court backs euro zone's new bailout fund
* Spain bond yields drop, may not need aid
* Apple set to debut new iPhone
* Futures up: Dow 66 pts, S&P 6.4 pts, Nasdaq 17.75 pts
NEW YORK, Sept 12 (Reuters) - U.S. stock index futures climbed on Wednesday after a German Constitutional Court permitted the ratification of the euro zone's new bailout fund as the region continues to battle its debt crisis.
* The court allowed Germany to ratify the new rescue fund and budget, but also gave parliament veto powers over any future increases in the size of the fund.
* European stocks rose to their highest level in 14 months and yields on Spanish and Italian debt fell after the decision. The FTSEurofirst 300 index of top European shares gained 0.3 percent.
* The decline in Spanish bond yields to well below 6 percent prompted Spain's Prime Minister Mariano Rajoy to say improved market conditions may make aid unnecessary.
* S&P 500 futures rose 6.4 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures gained 66 points, and Nasdaq 100 futures climbed 17.75 points.
* The Federal Open Market Committee is set to begin a two-day meeting on Wednesday. The central bank looks set to launch a third round of bond purchases this week to drive borrowing costs lower and breathe more life into an economy that is not growing fast enough to reduce unemployment.
* Apple Inc will be in focus on Wednesday as the company is set to unveil its newest iPhone, which is widely expected to offer 4G wireless technology for the first time, and a 4-inch display, longer than the current 3.5 inches. Apple shares gained 1 percent to $667 in premarket trade.
* Facebook Inc rose 3.5 percent to $20.10 premarket after CEO Mark Zuckerberg soothed investors in his first major public appearance since the No. 1 social network's rocky May IPO; he hinted at new growth areas from mobile to search.
* Economic data on tap includes import-export prices for August at 8:30 a.m. ET (1230 GMT). Economists in a Reuters survey forecast a 1.4 percent rise in imports and a 0.4 percent rise in exports.
* Later in the session at 10:00 a.m. ET (1400 GMT), investors will eye wholesale inventories for July. Economists in a Reuters survey forecast inventories to rise 0.2 percent, against a drop of 0.2 percent in June.