Tasks vs events

Average day of my salespeople is visiting accounts to show them products and take orders. Trying to understand the best way to record each visit so I can clearly see everyone's activity by customer or by lead, correctly dated and timed. Is entering tasks connected to each account or lead best way to do this? I am a little confused about open or closed task thing, just not sure how to categorize it. Also, if follow up is needed, how do you set it up so it shows up in the calendar?