If I am going to build a small ship, which direction should I build toward?
I find it's more important to get a solid, sizeable piece in early than it is to worry about exactly what that piece is. Since you're building in real time against opponents, part of the strategy is not letting them have the chance to take all the good pieces. Solid choices are most 4-ways, or cargo, or a gun/engine at the ship bottom. Avoid powered pieces if you can, until you know that you're going to want to build for/with them.

Avoid crew for the first piece if you can, due to epidemic. Shields and batteries become more useful with the expansion, where you can perfectly protect a ship with boosted shields. That said, if there's incoming laser fire that you see and you're going to have to deal with it, 

As you mentioned, 7 is the single most likely result. Having guns covering each 7 row/column is a good safety measure.

A couple of side/backwards guns are great for protection from meteors.

As with all ships, more important than the exact piece in the middle is that the middle is connective, and that the ship is built without open connectors.