Question about objects

I have some questions about monotransitive verbs and their usage. I don't remember exactly, but a monotransitive verb consists of a subject and a single direct object.

For instance,

1. I love you(direct object.)
2. Please say something to him(here "to him" is a prepositional object and "something is the direct object.)

This Wikipedia(http://en.wikipedia.org/wiki/Indirect_object#Types_of_objects) information says "Indirect object does not come alone. There must be a direct object before or after the indirect object."

Saying that, in some books the prepositional objects are considered indirect objects.
For instance,

3. Sing a song to her.
4. Can you help me to find my ring.

I am confused about the object pronoun "me." Is it a prepositional object or indirect object? If it's the indirect object, then is what said earlier wrong?

I have some basic idea about how to identify the objects. Asking a question with "what" to the subject gives you the direct object and on the other hand, if we ask a question with "to whom" to the subject, it will give us the indirect object.

Also, in "I love you" - is you indirect object then? To whom do I love? You is the answer.

Please help me with this.