The current version of RPH for RDR2 (2.97.1425.20915) fully supports the latest game version (1.0.1491.18). We only ever support latest one, so if you have an older game version you will have to use an older RPH version or just update the game.
I think you might just see general performance degradation from LML (vfs.asi) which is likely to occur on slower hard disks since there is more overhead per IO operation.
Many months ago R* changed some internals that broke most of the animal controls. There is an option in the trainer that attempts to revert some of their code changes to make it work again which you can try, but I have not tested it in a long time.
That's odd. Can you attach your RPH C# log file? Perhaps RDRFR does not play nice with the models for whatever reason.
To boost your rank, you would have to get more posts/likes etc.
As of now we do not have any immediate plans to update RDRFR. That being said, you might be able to use the Life of Crimes character customization and then go on duty afterwards.
You should be able to adapt my tutorial mod for riding with NPCs: https://www.rdr2mods.com/downloads/rdr2/other/26-tutorial-resource-npc-taxi-finished-project/