Hi friend!! To answer your questions:

1.) Yes! You discard the other two cards you don't choose for your project card.
2.) You will apply a value of +/-1 to any single die once per project. You cannot change which die gets this value; once it's applied, you cannot use it again until your next roll. "Wrap around" typically refers to the fact that a 1 could be -1 to make it a 6, as if the numbers were arranged in a circle. 1 is adjacent to 6 and vice versa.
As for how to create one, it's essentially a "perfect" roll for each range. The lowest of the low, the highest of the high, and a 7 of any configuration based on what the metal requires. This can be incidental during the course of play, but as you gain experience (more dice) this becomes more likely closer to the end of the game. In some of my playthroughs, I've managed to clear the client list and have a few turns to try to get a masterwork only to get it on the very last turn! It's a nailbiter!
3.) If your shelf is full when you would add an active project to it, you would simply discard the failed project, or discard one of the shelved projects to replace with the active project.
4.) Yep! You nailed it! Most often you'll be applying project cards that meet or exceed the client numbers, but occasionally you'll find yourself in a position where you need multiple projects to fulfill a client. In your example, the 2 project and the 5 project can, over the span of 2 turns, fulfill a 7 client! You've got this perfectly figured out :)  

Thanks for asking such thorough questions! Happy to answer any more if needed. Thanks for playing my game! 

-Jamie