1.) I think Jørgen Leth handles the obstructions the same way any one would handle them. At first he deems them nearly impossible but once he is able to let his mind wrap around the ideas for a while his creative process is able to take over. He thought the first one would be impossible but I believe it turned out to be great. Once he is able to get over how challenging the obstruction is he is able to use it as a strength instead of a set back.
2.) I think the obstructions are very helpful because they give structure. Some people are unable to work with no limits and that's too much power for them. In my personal opinion I like to have some type of structure or guidelines to help to shape a creative idea. Whereas, when I am given the sky and everything in it to create something I tend to encounter writers block.
3.) I think these obstructions can help us with our next project because they can give us some type of theme. Sometimes I think projects that are too open ended become very unorganized and messy. But when you set some ground rules and give yourself some borders I believe you can work with the challenges to create something incredible and organized. It's similar to writing a paper the better and more in depth your pre-writing and foundations to the paper are the more organized and better presented the information is.