For this season you probably need do no more than rub down the harder original paint and seal and prime well where it has been damaged,then paint it with a single pack paint. When time permits next winter you could strip off all the paint and start from scratch if you want to make sure the timber is in good order.
Dings and nicks are repaired using Boat Epoxy from Plastic Padding. After cleaning up the damaged area, stick some masking tape on one side of the board, over-lapping the edge, then lay on a generous helping of catalyzed filler and stick another piece of tape on the other side and use your fingers to kinda mould the filler to the right shape. You won’t get it right first time but a couple of episodes later you should be able to sand it down to a nice shape. If you are up to a little wood and metal-work the leading edge and tip could be protected by an aluminium or brass strip, screwed on and faired into the shape of the foil.
I have just done a Danish bush job on my centreboard; have a look at the WIT page penned I believe by a Dutchman who often contributes to this forum to be found at http://www.wayfarer-international.org/WIT/maint.repair.ref/CB.rudder/finishingCB.pdf The same article shows how to fit a stainless steel (very posh) edge protector to the foil.
If you would like to do your own Danish bush I could send you a chunk of Delrin rod (you can only buy it in lengths of 600mm or more so I have a bit left over). The advantage is that the bush prevents the bolt from pinching the centreboard through the case and if you get the sides of the bush turned up on a lathe (by a handy friend with a lathe in his garage), the faces are nice and square so water ingress is minimized even before you use the Grolsch washers. Also it is likely that the wood through which the old bolt passed has been saturated and dried a few times so is probably a bit second-hand, the bush allows you to drill the suspect wood away and replace it with epoxy and high-tech plastic.