also i deadheaded completely spent blooms thinking this would help new ones grow? (completely spent meaning turning very ugly or just the nub where petals used to be)

The roses will bloom again after the next round of shoots grows out.

The rose slugs (good diagnosis) are on the underside of the leaves. They have to be coated with oil or soap spray if it is to work. Easier just to wipe them off. Usually they don't become a severe problem because predators eat them.

You don't have to deadhead KO, but it will bloom somewhat better if you do. The idea is to prevent fruits from developing.

The original blooms were forced in a greenhouse, they want to grow roots now that they have good homes. Roses take 4 - 6 weeks between bloom cycles. Keep watering, hold back on the super-strength fertilizers. See this thread: Bloom Booster. A good organic fertilizer or a balanced fertilizer will serve you well.