You pretty much know if you have commitments to funding. You talk to people. You gauge market sentiment and the competitive landscape.
Then you are putting yourself in jeopardy on economic reality grounds. Even if the fine print says people can cancel, if everyone understands that it isn't really going to happen, then it isn't real.
I specifically wrote refutations to #2 and #3 up thread.
I understand. I nevertheless consider them to be issues of significant concern, especially when all is taken together.