G'Day Brian;
I think its all still fairly consistent with our previous discussions (?)
(I hope so, at least) ….
The key here, is to separate the 'Observable Universe' from 'The (total) Universe'. The 'boundary' of the Observable Universe is a 'Cosmic Horizon', (which can be more accurately defined by a Hubble Sphere and a Particle horizon). These are then analogous to a black hole's Event Horizon which is used to predict the behaviour of things furthest away from us (moving at or greater than speed of light).
The hologram bit is where it gets complicated because this shifts into an Information Model paradigm, and it is definitely non-intuitive.
Have fun.
Cheers