Did the oil can icon and red light just come on? (this is with the engine running, correct?) I would not think that a liter low on oil would be an issue.
As far as the oil leak there are a few common possibilities.
First, are you sure it is engine oil leaking and not chain lube?
If it is engine oil, the common areas are water pump base o-ring, clutch push rod seal or output shaft seal. You will need to pull the front sprocket cover to inspect. If the leak is not totally obvious, you will need to clean the area well, run it, and watch for new oil.