1. What is the difference between an mirror line and an axis of symmetry?
Axes of symmetry usually lie on a shape. A mirror line is usually part of a reflection of a shape.
2. Are there any other transformations besides reflection, rotation, translation and enlargement?
Yes, shear and stretch are other transformations.
3. Why do regular octagons not form a tessellating pattern?
The inside angle of a octagon is 135o and so when you try to put three of them together with no gaps or overlapping the angles add up to 405o and so they do overlap.See diagram below.
Regular hexagons tessellate perfectly
Regular octagons do not tessellate
4. What happens when an enlargement has a scale factor of 1?
Not much! The image will be the same size as the object and in the same place.