Is raising any one of the drives out of the water, while the other two are running/working, a problem?

If one engine stops can that drive be raised to eliminate drag,or does that cause a problem?

Maybe a better way to phrase it: Are the drives designed to raise from the water independently while the other two continue to operate and drive the boat?

Will play hell with the steering geometry fi you go to the point of bringing (1) out of the water.

Yes each drive should have it's own independent trim.

Seems like the middle would pull the outside in. Could potentially cause props to hit. Have heard this happen before. If you had a long way to go, I'd have to pull the prop off and leave the drive alone.

Trust me, you want to keep very close eye on the center drive in reference to the outer two. Play around with it on the trailer and take mental notes of what point bringing the center drive up will pull the outer two in enough to cause the props to smack. Also realize that when turning with the center drive higher, it causes them to smack even sooner than when straight. We have a Donzi 43 ZR with triple 700's/ NXT's and one time in shallow water, I raised the center drive a bit. Later that day, I thought I hit bottom because I was in shallow water and all 3 props were dinged. After props were repaired, did it again but in deeper water where I simply trimmed the inner drive too high. Finally realized what I was doing wrong after 6 very expensive cleaver repairs.

No problem with outboards. Kill the engine and trim it out of the water. Another plus for multiple outboards on center consoles that everyone loves to hate.