Do you plan to fiberglass the paddle, or just "paint" it with epoxy?
Either way, the paddle surface should be untreated, or treated with water-based wood dye.
Paint of any kind or some oil-based dyes will prevent the epoxy from forming bond with the wood.
If you want to fiberglass, the surface should be smooth. Bumps and ridges will make it impossible for the glass to cover the surface uniformly.
Planing is probably not enough, but I'd say even the 80 grit sanding should be enough for glassing. Actually, coarse-grained sanding may be better-the surface will have more 'micro-ridges' for epoxy to bond with.
Have fun!

PS. Has the Baltic thawed yet? I plan on visiting the old Hanseatic countries some time next year.

: Hi there on the other side of the world!

: Im going to make me a paddle. Then I started wondering what surface epoxi
: attaches best. Is it a 80, 400 or 1200 sanded surface? Or even planed?

: This thing "kayak making" is FUN!!!