5. Is it resuable ESLO lock nut?

Yes. In specific applications, we are not sure how many times it can be used, but we can say that there are many products that use the anti-loosing locking concept design. 

After 50 times of assembly and disassembly, we have not found There are signs of a slight decrease in the locking force.  

Under normal circumstances,as long as the internal thread  not corroded during use, it can continue to be used.