the half whisky barel will do just fine. Your B&B will eventually send out new plnts all through the barrel and fill it in. At that point, you'll need to divide it.
Any GOOD potting mix will work well for you just make sure your getting enough drainage.

And to divide it you just pull the new bottom growth? I am experimenting with rooting some from cutting, but my main plant has new little 'babies' around it. I tried digging one up and realized it was connected to the main plant since I couldnt find its roots.

I would like to take some of the new babies and put them in another planter, but was told its best to move only if it has roots.

The B&B should do really great in a half barrel.

Skrip,
You might want to wait a little while if the new ones don't have roots of their own yet. The new roots should come about quikly.
IF you want to try rooting a few cuttings, go ahead. I find that the Guaraniticas are some of the easiest plants to root.
Adam.

I have a little cutting in a tiny pot with miracle gro soil and a plastic cover on it. Looks like it is working a bit. It had a flower spike in the middle that was just growing, I pinched it off and stuck it in leaving 2 leaves on both sides of it. WHere I pinched it seems to be growing new little leaves. Im hoping in a couple of weeks I can plant it.

The new growth is a good sigh. It usually takes about three weeks to make sure it has enough roots to survive.