Enko can barely see the tree, assuming you mean the "tree lady" oak. It's a very large but only slightly less indistinct shape in a literal forest of large and indistinct shapes
The oak is about 100 paces (read: ~200 feet) from your small campfire. A campfire doesn't shed that much more light than a torch, which only has a 40 foot radius of real illumination. You're welcome to go closer to inspect it, if you wish.
You can, but you can't 'keep watch' at the same time. The ritual will absorb the vast majority of your attention until it's completed. It'll take ... oh, let's say 2 hours. That gives you a little time before and after, if you choose to perform it.
I realize this first night in the wilderness is going very slowly; after this, watches will be more condensed, probably into a single post unless combat occurs.
I figure it's like a TV show. The first time they show the whole thing, because it's character-building and people talking. After that they just skip over it because it's boring.