RE: Board - Sail selection
At least initially, until you get most of your skills back, perhaps a mid size Carve (111/122/133 ltr) would seem a really good place to start.
Since modern sails have more range and perhaps a little less overall power I'd think for 10-18 knots a 7.0-7.5 m2 rig would probably be the best.
Not sure where you are located, so I cannot know what your local "brands" are.
Sailworks Retro, Severne Gator, and several other "free race" designs would be good and they are pretty much "plug and play" to rig.
The Retro sails have a "tuning indicator" in the design, so if you use the correct mast, just downhaul until the "scallop" in the panel with the tuning indicator mark reaches the mark, and you have the sail all tuned for it's mid range. Retro's come with a one side adjustable outhaul system so you can make small tuning "adjustments" as you are saiing.
I would recommend an upgrade to the full 2 sided formula adjustable outhaul system as then you can tune your sail's power for whatever the conditions are "at the moment".
If the wind strength increases, or lessens, by more than 3-5 knots, a quick trip to the beach and a little more (or less) downhaul (the tuning indicator will let you know how much you've changed things) and you can get the full range out of your new rig.
Some other sails (besides the Retro) have tuning indicators so look around before you buy and look for a sail with this feature, get the correct or "best" mast and rigging/tuning your sail becomes very easy and it will be easy to duplicate your settings when you get the same wind conditions again.
So, while you were away from windsurfing, things got quite a bit easier and far more "user friendly".
Hope this helps,