2nd floor sitting area Coolply sitting area and porch issues

[Chiefnewell]

1) Why is the sitting area at different levels? This has coolply on it not decking boards. There is a 7-step down from the porch. Ceiling below is 6x6x5/8 

2) roof over sitting area and porch, same ht with gable roof to look at the lake. 

3) This is an existing house wind just took the railing off the side and roof. Just putting back the same. 

[Chiefnewell]

[Chiefnewell]

Here is the floor plan I forgot to attach and more images.

Floor Plan.zip