Hi,
1. Will be much easier, and you have time for a proper design.
2.
I cant recommend a WLC only deployment of 8.x to.
BUT if you want to setup one, you use VRRP.
But this will be a Master-Standby structure.
For example have a look at this:
https://www.flomain.de/2017/11/master-standby-arubaos-8/
Here are two screenshots I like to share to you
If you deploy a MM + WLC structure, be sure about the clustering.
As long as the two controller are in the same cluster profile, all load from all APs will be shared across them.
If you want the APs to be more sticky to one (because of different locations, bandwith between them, whatever), you have to configure them as standalone and set LMS/Backup LMS like before in the AP Groups.
But then, on the other hand, you have no seamless roaming...