Look on Dazzle's blog and you should see an entry with great tips on Juice storage. I always juiced in the morning and stored the juices in plastic bottles in our office refridgerator. When camping, I juiced a bunch of juices and stored them in my own cooler. We camped about 5 days and I did just fine.
I think the veggie based probiotics may be best, although I've heard that people use regular lactose based pbs. Since you're not digesting it, I can't see too much difference. Enemas have always worked for me, although they're certainly not fun. LOL :) I also use lax tea, once or twice a week, in place of the enema. The combination has given me great results.
I think the weight gain is typical. I don't think it's scientifically possible to put the weight on as fast as it comes off with Juice Fasting. I worried about that too after my last fast, when I recognized I was going way overboard on my eating habits. It took me three years to gain it all back (after only 5 months of Juice Fasting to lose it).
This round will be better for you. You've learned from your last fast. :)