For my first woodworking project, I am building bench with wood I found on the curb. Both my neighbor and a guy walking down the street said they thought the wood was at least 150-years-old. The walker suggested it used to be a floor joist. Anyway, my point is that it's an old and beautiful piece of wood, and I want to finish it in a way that preserves its sense of history. I really like the saw marks, for example.
Filling cracks. The wood has some cracks in it. I don't mind, but I don't want them to grow. And I attached the legs via dowels (based on this W.SE advice) and while it turned out well, there are some big gaps between the legs and the top. Do I need to fill these with epoxy or something for maximum durability over the years?
Finishing. I don't know anything about finishing wood. Based on googling, I don't think I want a stain. Rather, I'd like something that minimally changes the color of the wood---just enough to really bring out the texture---and that preserves it. I don't really know what my options are, how many coats to use, how to clean the wood before finishing, etc. Any advice is appreciated.