We did lose two of them with no explanation...we had seen them happily hopping only hours earlier and then found them dead that evening. :( Little Bean was quite upset when we found that two had passed away. We had a little funeral for them, and he started to cry. From what I have read, it's normal to lose some when they pass from tadpole to froglet, so perhaps that was just part of the deal. Either way, we know we did our best to take care of them.
Three were completely ready to be on land by the time we released them. As it happened, we ended up with two types of frogs--2 tree frogs, and 6 true frogs (living on land). We took the (semi) long drive up to the pond, and released them back into the pond where they were found. We spent the rest of the morning exploring the creek, and found quite a few other frogs that were the same size and type as ours, so we know they are among friends.
Here are our tadpoles on the day we caught them, a few weeks ago: