As for starting island - two reasons.

One being, UDA was interested in alfar and suggested it, the other being I know of at least one other island that will be super contested.

Finally, we had to pick one to start, so we did. We found what we needed in regards to good city spots.

However, that does not totally discluse the others, I would be interested to check out the SW island especially TBH.

Harbors seem kinda rare at the moment.. and honestly, other than fast travelling up and down a coastline there is no real reason to use ships, other than as seige weapons against people unwise enough to build towns on the water.

You can also use a friendly/allied hamlet to construct a ship, once its constructed.. unfortunatly it just sits in your pack and you can spawn it anywhere apparently.. so taking , holding and building up facilities for shipmaking off the bat is probably a nonstarter.