* cluster/unify is listed as Obsolete/legacy. This has been replaced by cluster/distribute. Cluster/unify had a single point of failure called the namespace brick.
Yes, thats true.
* cluster/replicate replaces cluster/AFR and allows n+ replicas where AFR appeared to only allow one.
cluster/replicate is synonymous to 'cluster/afr'. There were some issues sometime back with having more number of replica copies, but thats been resolved now.
* 3.0 config files do not allow on-the-fly changes as 3.2 does.
Config files remain same, but the 'glusterfs' process itself can re-read the config file from 3.1.x onwards where as in 3.0.x or earlier versions, it could read the config file only once. Due to this, with glusterfs 3.1.x + (ie, 3.2.x too), you can edit config files and make the process re-read it.
Regards,
Amar