Texturing in blender or UE4?

Hello to all the developers out there. I’ve been playing with blender and UE4 for around 50 hours now, so I’m quite new at it. I’m starting to get the understanding of everything. Yet some things I can’t really find the answers to.

Lets say I want to make a massive 3.D model of a tree, a massive model like a 100 meter high tree with a top that is maybe 50 meters wide. I want the player being able to attach a machine to the tree that harvests wood from the tree without the tree itself changes looks or properties.

I’m looking for the best way of doing those things performance wise.

So here’s my question. How much am I doing in blender and In UE

What program is the most effective for the texturing and in which program should I give the tree it’s properties? such as physics, wind properties and the property of being able to be harvested.
Is it best performance wise to make it real scale in blender or smaller and scaling up in UE as an example?

The reason I’m asking is that I want to learn the right way from beginning. Not just creating a massive amount of content to later realize that I have to redo everything for better performance.

Just to make it clear, I’m not asking how to do it. I’m more asking the way to do it. Not that it wouldn’t be nice if someone posted a complete guide for it.

I hope my English makes sense, and thanks in advance for all the answers.