FWIW.......
Thats a "look at me lift", there is no legitimate need off-road for that rockstar lift. That is a lot of lift for a heavy and top heavy Tiger. I can not imagine the cost down the road for tire replacement, balance and rotation, suspension parts, front end alignment, etc. Tigers are already tall, this lift may cause issues getting into NP, low bridges, trails with trees, heck even taking to your local tire store or mechanic they may not be able to get it in the shop or on the lift. Now, it is a 1 ton diesel with HD suspension components but, that is still a big lift on a heavy truck that a lot is going to be asked of it.
The kitchen cabinet/roof line normal tapers up at that point due to the raise in the roof. That gap is normal and has nothing to do with damage or leakage. My concern would be this vintage of Tiger doesn't appear to have the stabilizing block that supports the weight of the kitchen cabinets and that big ass tv onto the top of the bunk so, if the cabinets get over loaded or the vehicle does alot of rough roads the cabinets can get ripped out of their roof mounts.
I agree, I'm not sure whats going on behind the rear wheel......Some owners will cut that area out to install a utlity box but without better pix I just can't tell.
Lastly, this truck has been for sale for close to a year so It would lead me to want to see it in person and have it checked out. Buyer beware.