HSL You can buy daily tickets up to 13 days. For example, AB ticket (valid in Helsinki area) 3 days costs 18,00e and 6 days costs 31,50e. For you it is enough to have AB zones to commute to most of the places. From the airport you need ABC ticket. You can buy single ticket for that when you come from the airport to the city. You can buy tickets on HSL application or at tickets machines at the airport or railway station in Helsinki.
To Pasila (Business College) you can take any local train from the main railway station. Usually tracks 15-19 are easiest and fastest to reach when you come by foot to the station. From your hotel you can either walk or take tram to the station. If you download the HSL application, you can always easily find the fastest routes and timetables.
Traditional Finnish restaurants:
More tips on this site: Traditional Finnish restaurants | My Helsinki