The shadow of the strings suggests that they're not touching, but there looks to be a decided dip in the top behind the bridge. #Hard to tell. #Can you give us a pic from the side looking down?
Perhaps you mean that the top of the mandolin is angled down between the bridge and the tailpiece? #That is normal.
Many strings have a thread-like winding for an inch or two at the loop end, often the four lowest strings. #Is that what you mean?
The lightest weight T.I. strings would be very gentle on it. #J-73's could be dangerous. Anything heavier might easily turn it into bad kindling wood and would be right out.
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