I would never use a juicer as it would destroy the enzymes which would be a waste of money. If you use juice use a juice without 100% of the RDA. No more than 10%. Organic grape juice works well.
Yes. If you dilute it with water you will slow down the reaction and you could drink it throughout the day. Not sure about juice but it would be worth a try as Chlorine Dioxide has a disgusting taste. Grape juice masks both the acid and the ClO2