Congrats on your new Pop Up. You are gonna love it.
I am not sure about the dinette dimensions but I do believe the floor plan specs will say. It is about 72" if I recall so a 6' person can sleep there fine.
Your awning is about 13' so the add a room would be about 13X10 would be my guess. I did not get that option.
The standard X-Chock will fit fine. That is what I use and it makes the pop up rock solid. Those are one of the best things I bought for it. What a difference. I use two of them.
2006 HW256 (previous pup)
2013 Chevy Tahoe
Equalizer WDH 1000#