It's not a jeep... the warranty is good for the stated age/mileage (6/60 powertrain) regardless of previous owners.
Now if some stuff has happened or been done (or not done) that's a different story.
DO NOT CAP THE LINES!!!!!
the bvsv just controls when the evap purges.
It won't make any difference to speak of.
Put the lines together or run the canister line to the pre-bvsv port.
Having worked on a number of them, I'd say stay away on general purpose. They aren't real noteworthy as far as longevity goes, unless they're cared for EXTREMELY well.
They do have the good trans, transfer case and rear ends though.
Timing is adjustable. The curve is computer controlled, but advancing the timing, say, 5 degrees, will advance the entire timing map 5 degrees, minus knock sensor re****ation, of course.