During the sensorimotor phase of the child's development (from birth to 2 years old), the child learns about the world through his senses and the manipulation of objects. The main achievement during this phase is the permanence of the object, that is, knowing that an object still exists, even if you cannot see it. This requires the ability to form a mental representation of objects. Through mental representation, it is also possible for the child to understand that a model and the larger object with which it resembles represent the same thing.
If the child cannot understand these things, this child may be having difficulty with mental representations.
The answer to your question is True. The physical appearance of someone's genitals can indicate that he/she has an STD as most STD's have physical side effects.
Not really. I suffer from extreme social anxiety so I am the opposite, being anxious around strangers and more comfortable around people I know. Some people may find being around people who don't know them well less anxiety-inducing because they don't feel forced to open up or show their sensitive side. Just my theory, so don't take my word if you think something else :)