Of course, you cannot use superglue on styrofoam, you´ll have to use PVA or varnish for that.
Superglue is to be used on paper and wood. I use a very thin variety for that, which immediately runs into every nook and cranny - take great care when applying it. I´d suggest carving the basic hull shape from balsa wood, then seal using superglue, let dry; then, sand down any irregularities, clean the piece, re-seal, and you´re done.
I would not use unsealed wood with RTV (again). The silicone easily rips off the topmost layers unless sealed.