In determining the nature of the mitzva to dwell in the sukka, we must first distinguish between the first night and the rest of the Festival. The gemara (Sukka 27a) cites a debate between R. Eliezer and the Sages regarding how often one must eat in the sukka.
What is the optimal thickness of sekhakh – should one be able to see the stars through it? May it protect the sukka from rain and falling leaves? What if it allows in more sunlight than shade, and what if is under another sukka or under a tree? Finally, what are the laws of the sukka decorations and when do they interfere with the sekhakh?