1. The skillbooks have different rarity, matching the rarity of the chars. You can use higher books for champs of lower rarity, but not the other way round. So you could use a legendary skill book for your rare starter champ - but you definetly should NOT do this. If you don't have enough rare books to maximize all skills of your starter champ, be patient. So the answer to the first question is clearly NO (at least, if my interpretation of your question is right).
2. You should not follow the armor suggestions ingame. There are better ways to equip your champs in most cases.