Core is abs and back? Do you spend a lot of time on your core?

Yesh, because zombie apocalypse.

What are your main core exercises?

Not gonna lie, I have more to do.  I keep a 15-lb weight at my desk and I do things with it.  I start every day here:  

http://pandawhale.com/post/71294/7-things-that-will-happen-when-you-start-doing-planks-every-day

Planks really seem like an advanced move. 

They look hard but not so much.  Especially if you count really fast.  :)

Time to learn to count fast!

Trainers at my gym all agree if they could have ONLY ONE piece of gym equipment at home it would be the rowing machine.

I haven't used one of those in a while. How long is a good amount of time to spend rowing?

30 minutes, medium to high intensity. Here's a cool workout:

http://www.shape.com/fitness/cardio/cardio-fast-lane-30-minute-rowing-routine

Fascinating, they don't spend all 30 minutes rowing:

That's only 9 minutes of rising. 

Great cheat sheet btw: 

http://www.shape.com/fitness/workouts/exercise-cheat-sheet