Hi Asia, "Balls to the wall" usually means the person is very person or is overwhelmed with the amount of work he/she has to do. It is a very common phrase used in American kitchens, along with "in the weeds." "Bold nature" in this context likely means a fearless character, or at the least willing to do something despite the possibility of negative consequences.

This website has forums and a fairly level-headed discussion of expressions: http://www.phrases.org.uk/bulletin_board/41/messages/951.html

The expression "balls to the wall" comes from aviation. The throttles had ball shaped tops. When they were going full speed, the balls were positioned very close to the planes' firewall. Hence when the "balls" were to the wall, the plane was at full speed. Bold nature. In this context, nature means a characteristic or a feature. In this case a feature of the project is it's boldness or daring. A project that aspires to accomplish a lot.