Place the shrimp in a shallow bowl and drizzle with 3 tablespoons of the olive oil. Add about 2/3 of the minced garlic, season lightly with salt and pepper and combine well. Set aside while you cook the orzo.
Heat the remaining 2 tablespoons of olive oil in a sauté pan over medium heat. Add the onion, season with salt and pepper and sauté until soft and translucent, 5 to 6 minutes.
Add the dry orzo and stir to coat with the oil. Continue cooking for 2 to 3 minutes, stirring frequently, then add the remaining garlic and cook until fragrant, 1 minute more.
Deglaze the pan with the wine, scraping up any browned bits that have accumulated on the bottom of the pan.
Stir in 3 cups of the chicken broth, cover the pan and reduce the heat slightly. Cook, stirring occasionally, until the broth has been absorbed, 5 to 7 minutes.
Continue adding broth, 1/4 cup at a time, until the orzo is cooked to your liking. Stir constantly at this point and let each addition of broth absorb completely before adding more.
Once the orzo is cooked, stir in 2 tablespoons of the lemon juice and season to taste with salt and pepper.
Plate individual servings of the orzo and set aside while you cook the shrimp.
Working quickly, wipe out the pan and return it to the stove over medium-high heat. Add the shrimp mixture and sauté until pink and opaque, 1-1/2 to 2 minutes. Tip: Use a rubber spatula to transfer the shrimp to the pan so you get all of the oil and garlic marinade.
To finish the Garlic-Butter Shrimp: Add the butter, parsley and remaining 2 tablespoons of lemon juice to the pan. Cook just long enough to combine well and melt the butter. Divide the shrimp between the plates of orzo, spoon the pan juices on top and serve immediately.
To finish the Greek-Style Feta and Dill Shrimp: Add the butter to the shrimp and as soon as it melts, add the diced tomatoes, dill and remaining 2 tablespoons of lemon juice. Combine well, then divide the shrimp between the plates of orzo. Spoon the pan juices on top, sprinkle with crumbled feta cheese and serve immediately.