Seems to be fixed since 14w03b. It still happens with 14w02c, but I wasn't able to reproduce it with later versions. Neither the same setup nor a different one.
Updated affected versions, still valid in 1.7.2 and 13w48b.
Yes it is, Just testet it and updated the versions.
Yes, you could also insert one or more (1-tick) repeaters into the input wire, that makes no change.
Seems to be fixed since 14w03b. It still happens with 14w02c, but I wasn't able to reproduce it with later versions. Neither the same setup nor a different one.