Hi Kim,
The second commandment (Exodus 20:4) says, "You shall not make for yourself an idol, or any likeness of what is in heaven above..."
Therefore it is a bad idea to make an image of God, whether in 2D or 3D, to worship it.
People wear cross ornaments for many reasons, most likely that they are expressing their faith in Jesus by wearing jewellery representing Him. No, wearing a cross does not protect its wearer from evil at all. Better that a believer puts on the armour of God as described in Ephesians 6.
Not all pictures of Jesus show Him with blonde hair and blue eyes... some show Him as a dark-skinned and dark-haired man with dark eyes. We humans tend to create God in our own image; that extends to images of Jesus as well. There are no Scriptures describing the details of his colouring. Rather, "His appearance was marred more than any man, and His form more than the sons of men" and "He had no stately form of majesty that we should look upon Him, nor appearance that we should be attracted to Him" (Isaiah 52:14 and 53:2).