1) the color:
a result is shown green, if the speed, that is shown in the result was verified by the client, so you can be sure of its connection speed

2) the requerying:
If LimeWire is trying to download a file but the remote host is busy, it will automatically search for an alternate location. After requerying it waits a certain amount of time, since emitting query after query does not return more results (since more clients are rather unlikely to come into your search horizon).
The requerying will be improved, once LimeWire starts looking for the hash of a file instead of the file name, this feature is to be expected to be ready in the next weeks.