Answer to Question 1
The absorption of cold water is very slow in nylon. Furthermore, tow ropes are usually not totally submerged for long periods of time and therefore do not have
high absorptions. Furthermore, nylon ropes are seldom pulled to their limit in this application so the small decrease in tensile strength is not critical.
Answer to Question 2
Polyimide film has a very high temperature capability. Then as it might degrade, rather than melt, it remains a solid that keeps the electrical conductors separated. The char that is formed may eventually conduct, but char formation is usually a slow process.