Should the front foot stay down during the back swing ?

There are some pros who say the front foot should lift to enable you as you say to turn better and that the start of the down swing should start with the left foot (for right handed golfers) being planted down. In this instance I don't think this is right or wrong if it works for you fine carry on.

Totally agree. I have started lifting heel to save my back, and only keep it down for wedges.

Also gives you a good thought at the top of the backswing. Plant heel back down , and everything else should follow. I have been known to forget that, and it leads to a massive early extension.