Issue 1 is actually an intentional behavior. Users can be distracted if red wiggly line appears while typing. However, the next version will show red wiggly line if the cursor moves from the bottom position to another position.
Issue 2: this will be fixed on v17.7.91.
Issue 3: I am not sure exactly what this means. Type “Capitl”, and do you want EmEditor to show “capital” instead?