As far as material for a stich and glue type kayak goes, nothing really beats marine ply Okoume for strength and looks. I have had very good luck with imported 4mm from Israel, (British standard-somthing or other). It's worth the little exta effort and cost. Forget Luan.

As far as the pre epoxy treatment goes, I think the trick is to pre-warm the hull or deck prior to applying the resin, so as to avoid adding heat to the wood, but rather have the wood be cooled by the epoxy, eliminating the need for a pre-coat. Work with small quantities of epoxy until you can judge the heat of reaction, your work rate and abilities.