NSNP Skilled worker stream

Hi everyone,
I am on the process to apply to NSNP under skilled worker category. On the guide to apply, it says the employer has to provide proofs of support to the immigrant employee. My employer wrote me a letter of support saying that he will take care of accommodation for me as well as assist me whenever I need. I don't know what else should I ask my employer to prepare for me except for the letter of support.
Finally, for what documentation my employer should prepare to demonstrate the employer's business is a food workplace and business practices? I got a job offer from a small privately-owned business therefore I really want to make sure me and my employer has enough documentation before I submit my application.
Thank you so much for your helps!