If it is a EOS EF lens it should work. There is a conversion factor of 1.6 to keep in mind.
That makes this lenses focal length longer than what it is marked at by multiplying the number by 1.6. For example if it is a 55-170mm film lens used on a digital slr it would work as a 88-272mm lens.

Along the side of the card is tiny slider switch that can easily get flipped to the ON position that write protects the card. Moving it to the OFF position should take of the problem. If this doesn't work please re-post question so I can look into other possibilities.

8mm, High8 and Digital 8 are no longer made. As for repairing the old unit it might be more expensive to get it working again than is worth putting into it.
You might want to look for a used unit and get those old tapes copied to a DvD. There is still a few places on line that have some. Most Digital 8 will also play back 8mm tapes.
There also might be a Duplication House in your area the could convert the tapes to another format for you.

Elements in lenses are a very complex construction to correct for optical aberrations. The wider the angle of the lens the more complex the construction and in most cases the number of elements...or lenses inside the lens housing.
In the case of a Zoom lens that goes from 55mm to 200mm for example, the tube of the body will extend and move the lenses(elements) farther away from each other to enlarge the image before it exits the last element and imprints on the digital sensor.
If you have ever used a magnifying glass to focus sun light on a peace of paper to burn it this is a similar process. Now imagine a lens focusing on another lens and than another lens making that spot of light different sizes.
To see illustrations of lens elements try Google and Wiki.