以我理解只要 submit 的文件有齊IRCC 要求的資料就ok
i.e. job title, duties/responsibilities, job status (if current job), the dates you worked for the company, the number of work hours per week and your annual salary plus benefits.
if you submit employment contract (with details of job duties, working hour etc), I guess it is necessary to provide at least the standard ref letter when you left the company (with signature of ex-boss / HR), to prove the duration you have actually worked.
you may call to ask again
i did upfront medical in june, ITA letter will suffice
for me, UCI number first appeared in the request letter for police cert, which came after AOR and med passed
impossible to have this number at the moment unless things changed in these few months.