2nd curtain with YN 560 II?

I'm going to be shooting my first indoor venue soon, which is the complete opposite of what I normally shoot.

I'm going to be picking up my first serious flash, a yongnuo 560 II

On a 10D body which limits me to ISO 1600,

I want to do half the show where I kill the ambient at F4 and 1/200(iso and flash power balanced to that)

The other half I'm going to want ambient light, so maybe 2.8 at ISO 1600 and whatever shutter speed I get. I want to stop motion with the flash.

The trouble is I cant get the flash to stop the motion in first curtain, using second curtain I get it perfectly.

I've just been using my pop up flash for testing, will more power stop motion?

Better yet can I setup the 560 II to fire at second curtain? thanks!

There is no way to use 2nd-curtain on the 560, as it is a manual flash. 2nd-curtain sync is only available on flashes with ETTL.

Thanks, can I stop motion using the flash in first curtain.

Is just adding more power what's necessary?

Still new to this whole strobe thing.

For what you are shooting, it shouldn't really matter if you are using 1st or 2nd curtain sync. The only time 2nd curtain sync really matters is if you are going to have a lot of unidirectional motion (think a car driving past you). In the case of a car, you want it to look like the car is moving forwards, with the blurring behind it. With most applications, including yours, you really won't see benefit from 2nd curtain anyway. I'm not sure why you are running into a situation where 2nd curtain is freezing the subject but 1st curtain doesn't...there must be some other settings that are different here.