So I find 100's of threads about migrating; however, I find few that are exactly what I need.

I am currently on 4.5.11 network edition. Due to server HDD failures, I am needing to migrate to an entirely new server - this is not just update to the newest version but a server migration.

At a high-level, my plans are:

(0) procure new server
(1) install newest version on Zimbra
(2) configure new Zimbra
(3) establish SSL certs, etc. on new server
(4) export all account data from old server
(5) import all data into new server
(6) edit some 80 DNS record to point to new server IP address

My concerns are:

(1) I installed my current version some 5 years ago and forgot about it. I am not a mail admin. I have literally no clue how to administer Zimbra any longer
(2) unsure what I need to do to establish licenses for new version - I have not talked to anyone @ Zimbra in 4 years
(3) the export, copy, and import process could take days - or at least many hours; thus, I am concerned how to ensure I get all of everyones mail migrated over

Any guidance, assistance, or input would be greatly appreciated. I have a few days to plan this out before I must start and I am trying to ensure it goes as smoothly as possible.