banned ip (1000 more) using iptables

I had roughly 1000 ip that need to be banned from my server using iptables.
Question is :

1. Do you think this will causing high load on my server - putting 1000 ip's in the iptables ruleset ?
2. How to add that 1000 ip easily ? What file should I edit
or i need to do it manually using iptables -I INPUT -s xxx -j DROP
3. what happen if my server crash, do i need to enter these IP again ?

 

 

 

 

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