i am pretty sure if you steal a ship you only get the stock standard version

i.e. if you steal a cielo you get the embolden ability but not the designate target ability, regardless of whether the other player has researched it or not

same works the other way around, if someone steals a ship from you, he wont have any researchable abilities, regardless of if you have researched them or not, so there is no need to be fielding Guardians without the repulsion ability researched (once viable, of course)

hope that helps

Domination is the Rapture Battlecruiser's level 6 ability.

The Revelation's level 6 ability is Provoke Hysteria, which drops a planet's health by 40% of its max and its population by 40% of its max over a time period of 40 seconds.

Obviously, when in doubt pick the most expensive unit.  Carriers and heavy cruisers make your best choices.  Aside from that, support cruisers are your best bet.  Make sure to pick one with lots of anti-matter left!

Domina Subjugators restore hull.

Yes, but the cooldown on that ability (Perseverance) is one minute, so its not very practical to allow them to make up a large percentage of your fleet.

What is good about that ability is that it renders the target ship immune to disablement for 40 seconds (or until the Subjugator itself is disabled).