You could do that, but we were concerned that by directly connecting the buckets, any pathogens or diseases could move freely from bucket to bucket.
No, that's a great idea. What we meant was that using a liquid fertilizer applied from the TOP would not work well in our opinion.
Yes, you should use just one float value for the entire system, not one float value per bucket.
Please see "Automatic Watering Part II".
The automatic watering system is working great. After we set it up, we've only spent about 5 minutes on watering during the past month. We're making a video to explain it, but we're leaving for a family vacation so it may not be finished for several weeks.