What’s the budget and the value proposition? should be #1. Projects without a clear purpose (happens way more than you might think) are sinking ships you've got to get away from.
I would add "Make sure every stakeholder has the same idea what the project will be". I have seen a lot of projects where once you talk to all stakeholders it becomes pretty clear that there is no shared understanding of what we are trying to achieve. Especially be wary of senior managers injecting their pet ideas.
Clues this might be happening: senior managers pulling you aside to discuss their ideas for the project. Getting different questions on project updates than the goals you're building towards in scrum. Constantly changing short term goals.