I love those cards, they are great fun to read. You need a large cup of tea, and probably an hour to get the whole reading!
1. You'll need all 25 cards. Always.
2. No
3. They are very much like Lenormand, with 15 extra cards
The timed idea is from the Lenormand. You may use them for a monthly reading, but some cards point to some later point in your life.
4. I read the last card, and all 4 pictures first to get the first impression what this spread will be about. Then I read from left to right. It does not really matter, as long as you find all the pictures.
The book is great though, full of explanations. You've picked some great companions! I have given up asking specific questions, it is like visiting a friend who gives you a general outlook towards your life.