update target table

yes we can , it is the just that update strategy is used for conditional updates, and the update option available at the mapping level in the target is update without any condition.

Yes, By using session level properties.
In that use follow the steps

Session --> Edit --> Properties --> Treat source rows as --> Update

and also you should check options in Mapping --> Target --> Update (any of this according to your problem)

You can find the options like
Update as Update --> it is update your original record
Update as Insert --> it is going to insert new record with update of that row
Update else Insert --> if record exit than update else insert