I agree on making the detector more useful, with a wider radius.
More mines and/or a longer lifetime for mines will totally ruin a lot of maps. Right now I have to stay alive to keep my mini-minefield active, which is OK. If it doesn't matter whether I die a lot, or stay alive, I can spam mines everywhere and control a (large/important) part of the map. On Sidi Rezegh for example, you can mine off an antire flagzone by yourself if you place them carefully. So that means 1 guy can block the other team's advance. But, when you kill him, just wait a tad and there you go. Imagine the clusterf*ck when it doesn't matter whether you killed him or not...