I don't quite understand the meaning of the book, please.
The books at the beginning are a part of the puzzle to get the Lust book Roselyn wants to make costumes, then the books can be taken out and interacted with (just like you do consuming a potion) to get a semi-plethora of lore. Gets you to know about the monsters, history of Valencia and boundaries, and about the place you go to win the hearts of the women when they have doubt or question themselves.
A to Q1: From what I know (and has been said in posts on Patreon and the Discord Domain), 1.4.3 is one of the last (for now) extra content before the final push onto Endgame. Next version should be focusing on getting to endgame.
A to Q2: What do you mean by that? And which Goddess are you referring to? If you mean Minerva's mission (after reaching Passion Level 1) to go save the Goo Kingdom, that was developed and finished in version 1.0.1, the current mission 2 (after reaching Passion Level 3) is not available yet, it was an ability necessary to get the Shell Charm but will be (perhaps, take me with a grain of salt on this) pressed on in the next version.
A to Q3: You cannot really cut the trees in the game... Oh, you mean the giant logs cutting access to two areas? That will be post Endgame.
Hi, I just answered this question (somewhat) in "A to Q2". Repeating, it cannot be completed just yet because it is not available. After reaching Passion 3 Minerva gives you the Dive Power, go to Valencia Coast to (eventually but not currently) start the Passion 2 - A Wet Encounter (which is funny because not only are you diving into water, it will involve water creatures as well! Among another "wet" if you catch my drift. ^_^ Oh the puns!).