An immigration application is like a test, you don't exactly now how to answer every question they way you prof wants, but you have to be as precised and detailed as possible so your answer is both correct and, more importantly, as close as possible from what the prof expects. So I keep saying: Provide them with DOCUMENTS DOCUMENTS DOCUMENTS. as many as you can, as as detailed as you can, especially for things like work experience. I didn't get a single doc request. What they want in the end is the same thing we want in our researches, we want evidence. Tackle the phd application as if it was a paper where you have to be very scientific, very precise and, at the same time, written with integrity (that means, dot not claim things you don't have like money or work experience if you don't have it) and written in a way that is both persuasive and easy to understand for a layman.