This card says to enhance your play area. It says each unit you control gains one (Black Blast Icon).

My question is that once this card is played, do I remove it after the round is over, or do I leave it in my play area?

It just seems like over kill to leave it in play continuously. I believe the only way you can remove an enhancement is with a special type of card like event or something. Is that also correct?

Any card that says Enhance your Play Area stays in your Play Area until some other affect removes it. That's how you can generate up to 8, 9, 10 resources a turn with Enhancements that provide resources as the DS player to play out Capitol ships.

as was said above, enhancements stay in play unit something says otherwise, be it enhancement removal or something like bounty that has a couple ways it leaves play.

orbital bombardment may seem really powerful, and at times it certainly can be, but it's cost is very high, and will generally be the only thing your putting out which could potentially allow your opponent to gain control of the board or get superior board presence. It's one of those cards that has a time and a place to play, which tends to generally be mid to late game to finish out a game by bumping the dial with destroyed objectives, otherwise, it's not a bad edge card with 2 icons.

Yeeeeep. I blew up an Objective to win a game that only needed 4 damage because of Grand Moff Tarkin with Imperial Vader, Orbital Bombardment, Devastator and a couple Stormtroopers. I think it came out to close to 18 damage that would have been dealt to the Objective. It's a fun late game card.