It greatly depends on business requirements/drivers behind DR solution.
- What are time requirements for failing over to DR ?
- What are topology conditions (will the DR replicate IP scheme) ?
- Is it Hot or Cold DR ?
Looking at the task list you've received, seems like a Cold DR - that is, building a working environment at DR site from scratch. Again, if time constraints allow to set up firewall from scratch with new IPs/topology/rules, then it can take some 30-40 minutes to do so. Exporting/importing firewall policy from existing FW to the newly installed one, IMO, would be of dubious advantage - if IPs change, and of course they are used in the policy, you'd have head ache to fix the policy.
Most of DR procedures I've seen though, require replicating the LAN topology 1 to 1. It does not necessary include firewall if the firewall is used just to connect DR to the Internet, then possibly set up some way to access LAN of DR behind it.
The Hot/Real time DR would include DR site having the exactly same LAN topology with ongoing replication of data/services from the main site (usually via point to point link with the main site and some data center technology LAN extension technology like VXLAN/OTV of some sort, or just plain subnet dividing) with WAN IPs advertised via both (Main/DR) sites at the same time, so when main site fails, the DR takes over by the fact that production IPs get advertised (via say BGP) from DR site, and in this set up the firewall can have different IPs as it only provides perimeter security, not accessibility to production IPs.
Cold DR, on the other hand, would mean rebuilding the production environment from scratch at the DR site, possibly transferring WAN IPs of the firewall as well (with the ISP help). In such case, backing up existing firewall would be more logical - even using just migrate export, so after the fast clean install on DR site, you would import firewall config and be ready to go.
So, you are asking the correct questions, but only those designing this DR exercise can answer them.
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