I'd say all of your are correct. Here is a list of rules from the Chicago Manual of style. As noted, the biggest area of disagreement is with prepositions of 5 or more letters. Some put all prepositions in lower case; others capitalize those of 5 or more letters.Originally Posted by Mixus7
NIVA follows the general rules for capitalizing words in document titles set out in The Chicago Manual of Style (with one minor exception—see the note in rule 3):
1. Always capitalize the first and the last word.
2. Capitalize all nouns, pronouns, adjectives, verbs, adverbs, and subordinate conjunctions ("as", "because", "although").
3. Lowercase all articles, coordinate conjunctions ("and", "or", "nor"), and prepositions regardless of length, when they are other than the first or last word. (Note: NIVA prefers to capitalize prepositions of five characters or more ("after", "among", "between").)
4. Lowercase the "to" in an infinitive.