RE: How much wind to get planning?
I'd guess you will get planing (with good technique and a bit of pumping) at about 10-11 knots.
The Carve 144 is only 78 cm at it's widest and only 52.1 cm 1 foot off the tail and you are sailing on fresh water.
The stock 48 cm Drake Freeride Flow 480 fin would be OK for more powered up conditions, but the same fin in a 52 cm or a 54-56 cm
vertical planform fin will sure help to get you planing earlier.
The bigger fin will diminish the "loose and turny" feeling of your Carve 144 a bit, but better to get on plane and have a bit more speed and upwind ability when the winds are marginal.
At a solid 12 knots, you should be fine with the stock fin and will plane up pretty easily.
Hope this helps,