Thaw shrimp, if frozen. Peel and devein shrimp, leaving tails intact. Rinse shrimp; pat dry with paper towels. Cover and refrigerate until ready to grill.
With a sharp knife, cut off the top 1/2 inch from garlic bulb to expose the ends of the individual cloves. Leaving garlic bulb whole, remove any loose, papery outer layers.
Fold an 18x9-inch piece of heavy foil in half to make a 9-inch square. Place garlic bulb, cut side up, in center of foil. Drizzle bulb with 1-1/2 teaspoons of the oil. Bring up opposite edges of foil and seal with a double fold. Fold remaining edges together to completely enclose garlic, leaving room for steam to build.
For a charcoal grill, arrange medium-hot coals around a drip pan. Test for medium heat above the pan. Place garlic on greased grill rack over drip pan. Cover and grill for 30 minutes. (For a gas grill, preheat grill. Reduce heat to medium. Adjust for indirect cooking. Grill as above.)
Meanwhile, thread shrimp onto long metal skewers, leaving a 1/4-inch space between pieces. In a small bowl combine the remaining oil and 1 tablespoon of the lemon juice; brush over shrimp and vegetables.
Add skewers to grill over drip pan; add vegetables to grill directly over coals. Cover and grill for 8 to 10 minutes more or until garlic is soft, shrimp are opaque, and vegetables are tender, turning shrimp and vegetables once halfway through grilling. Remove from grill. Cool garlic and vegetables slightly. Coarsely chop vegetables.
While shrimp and vegetables are grilling, cook pasta according to package directions; drain. Return pasta to hot pan.
Squeeze garlic pulp into a small bowl. Thoroughly mash garlic pulp. Add butter, salt, and black pepper; mix well. In a large bowl combine pasta and garlic mixture; toss to coat. Add shrimp, vegetables, remaining lemon juice, and cheese; toss gently to mix. Serve immediately. Makes 4 servings.