All of that would be awesome!
I would absolutely love for warlocks to interact with their patrons narratively - and not just once for the entire story. I think out of all the classes, except for the cleric of course, the warlock is really defined by the entity with which it has formed a pact. Also, I REALLY hope that spell visuals will be altered based on the patron (fiery effects for fiend, dark celestial effects and tentacles for Great Old One).
Powers are supposed to feel and look very different depending on the patron, yes. Lorewise, it is confirmed that depending on whether your patron is a Fiend, Archfey or Celestial the visuals do look different.
Since that is likely a lot of work, I am guessing we will get a lot of spells in common regardless of the Patron, which might be a little awkward, I think specially if you choose Archfey or Celestial, since the first would be very nature, whimsical, feywild magic, and the second one would be lighter, holier, divine-like... And then a few patron-specific spells, which are the ones you can find in E5.
