"A:3/5/4" means "approved, 3 direct replies, 5 total replies, 4 visible replies"

"FA:9/25/20" means "front-paged, approved, 9 direct replies, 25 total replies, 20 visible replies"

I think the "v3" means that it has been edited twice since posting (maybe three times).

Update: see below for the real meaning of [v3].