If your paper has already been handed in, I apologise, but I'll answer anyway. I'm also presuming you're asking about John Foster and not Allen.

Dulles's impact on Eisenhower's foreign policy is a contentious issue among historians, with the orthodox school believing Dulles completely handled foreign policy, the revisionists arguing it was all Eisenhower, and the post-revisionists being equally divided (obviously this is a bit of a simplification, but it's just a brief overview).

Before I begin anything else, I just want to be sure that when you're dealing with the Guatemalan coup you don't over emphasise United Fruit. Many people with a passing interest have made the mistake of not examining archival documents closely enough and have concluded that since both Dulles brothers had a relationship and investments in United Fruit (and indeed a great number of high up Eisenhower officials held stock in the company) that the Arbenz coup was a pure and simple example of corporate influence causing international intrigue. There is almost no evidence that United Fruit had anything more than minimal influence in the coup. Indeed, Cullather's "Secret History" shows that both the State Department and CIA had very little problem with Arbenz's agrarian reform as it impacted United Fruit. I'll leave it at that as regards Guatemala.

Other instances Dulles impacted Eisenhower's foreign policy then. The most significant has to be in Egypt, where Eisenhower effectively gave Dulles free rein until the actual Suez Crisis. Dulles misread Nasser on a monumental scale, ignored (as he almost always did) the consequences and long term play his actions would have, and created a scenario in which the obvious-to-all-but-him outcome was that Nasser would move closer to the Soviets.

How the Eisenhower-Dulles relationship worked, to simplify greatly, was that if Eisenhower had an interest in an area or subject, he'd direct Dulles and give orders. Also, in a crisis (Taiwan Straits, Suez, Berlin, Atomic Tests etc.) Eisenhower, so long as he wasn't incapacitated, had total control and exercised complete direction over Dulles. This meant that Dulles sometimes caught flak for being lax or short-sighted, such as when Perez Jimenez was granted a visa and basically asylum in the U.S., and, after the Caracas Incident, Eisenhower demanded to know what Dulles had been doing.

However, if Eisenhower wasn't particularly interested, or a crisis wasn't impending, Dulles enjoyed almost total freedom and direction. Dulles understood how Eisenhower saw the Presidency - the President was meant to make decisions, not direct every little thing. He also understood that Eisenhower was far more interested in economic and military matters than actual down in the dirt foreign policy issues (excepting Europe). So if Eisenhower wrote to Churchill once, pushing for decolonisation, Dulles knew that even without Churchill rebuffing Ike, Eisenhower didn't care about the actual process. This meant Dulles could mention to French and British officials that they ought to consider working more respectfully with their colonial populations, but would go right along with plans that stressed stability rather than actual decolonisation.

Dulles's handiwork can be seen very clearly into 1958, where Eisenhower's policies stressed short-term stability in the world with an almost heroic disregard for the long term consequences. In the latter parts of 1958 into 1959 when Dulles's health and influence deteriorated, a discernible shift in Eisenhower's policies occurred. In Latin America, Eisenhower started actually acting upon the advice of Nixon and Ike's brother Milton, and slowly began the process of showing preference for democratically elected governments over friendly dictators.

The reason for the shift is that while Ike respected Christian Herter, he didn't believe Herter to be as capable as Dulles. Dulles had specifically stated to Eisenhower that Herter was the ideal short-term candidate to run the State Department, and that he wouldn't have recommended Herter if he'd be expected to serve for more than a year and a bit. Thus, as Herter took over, Eisenhower started taking a greater interest in day-to-day foreign affairs. This meant he started seeing more and more the mess he and Dulles had created by stressing stability with disregard for long term consequences. It also meant Ike saw that the State Department, and officials like Nixon had been warning and worrying about these long term problems for quite some time with little response from Dulles.

Greenstein's "Hidden Hand" can be taken, for all its flaws, towards seeing how Eisenhower ran operations. If he saw a reason to be involved, he would almost displace the official in charge, treating them as order carriers. If he saw no reason to be involved, he'd trust those officials to follow his often very vague guidelines and let them go about their business as he saw fit. Take Ezra Taft Benson (Agriculture), as Ike had almost no interest in the department, and trusted that Benson was anti-New Deal enough to do the proper thing, Benson was basically (for the most) left to his own devices, and was surprisingly oblivious to his fellow Secretaries and the politicking in the White House. He was completely flabbergasted when Nixon, then running for president, endorsed an agricultural policy that ran counter to the one Benson had been pushing.

I could go on and on about this, but to take a fascinating and frustrating figure and simplify it - Foster Dulles followed orders when given, but never surrendered his personality. Thus, though instructed to try to find a satisfactory settlement over Vietnam, Dulles went out of his way to be an ass, famously refusing to shake Zhou Enlai's hand and glowering throughout the entire negotiations. Dulles and Eisenhower agreed on most things in foreign policy, the only exception being that Eisenhower demanded that Dulles take a less overtly aggressive stance, and Dulles mostly accepted that.

If you just want a list of Dulles exercising influence - Iran, Egypt, Africa, OAS, Berlin (he and Adenauer were tight), Britain (the British almost universally disliked Dulles and loved Eisenhower), Indochina, Japan, Korea, Taiwan. I could go on, but this is a fair, if very broad overview. For further reading see Ronald Pruessen, Richard Immerman, and the Pach and Richardson volume on Eisenhower. Best of luck.