I like David's comments above and think that you should select a simple large (12x24") tile for your fireplace, light or dark.

Hebel is preferable.

I like the look of horizontal long run iron would this be a good choice for a house which is exposed to salt bearing southerly wind. Would it be more expensive than traditional wood?

We asked a similar question when we bought our piece of bare land. We were advised that building a simple shape would reduce costs... so we've built a t shape. Single story is almost always cheaper. We have a builder who is happy to let us do a lot of work with him. We also choose to live on site, which saves us a lot in fuel. The kids and I clean up the building site most days. We've been able to separate the rubbish out between actual rubbish and recyclable material. As for cladding, we were going to do a mix of corrugated iron with plywood board and batten. But given some of the additional hassles, I don't think there's much in it cost wise. However, in saying all that, we chose to invest in long term benefits, so our house is exactly what we want and should be cheap to run. We were hoping to build for $1800 /sq m but we're still coming out at about the $2000 mark.