You will see the healing machine from "Quality" once more. Part of the reason for that story was to set up something within the B5 universe that will come in handy a long time later (but I'm *not* going to have it lying around indefinitely; it would cause lots of long-term complications).
(Some TV shows foreshadow/set-up stuff an act or two ahead of time; we do setups a full *year* ahead....)
Never saw "Star Blazers," so the Valen name has no relation there.
No idea on coming laserdisk prices.
When Zathras shows up in time, it'll definitely be recognizeable as Zathras.