Hi,
one of my letter of employment is super easy. in left corner all details about company (adress, name of boss, phone numers etc). Then few words about details my work (who, when, NOC and annual salary) and on botton signature. i didnt provide bussiness card, because this company is small and they dont have any. As well boss didnt put stamp, because he lost one and dont have time to do new one. All letter was on piece of paper, without special graphic logos or something like this. My backround is in progress, so we will see what imigration will say about it.