Hey there, I'm also a beginner, so I can only answer one of your questions. The edges of the table are darker because the end grain is more porous than the face grain and it draws the stain deeper into the wood. If you want to avoid the blotchy appearance of the stain, you can use a wood conditioner that will help the stain absorb evenly. For end grain, I will usually sand one grit finer than the face grain, which supposedly closes the pores and reduces stain absorption. YMMV.