badly placed house and water harvest?

I am looking at buying a 5 acre property. Half the property is a steep hill that flanks the entire length of the property. The other half is flat in a depression in the natural landscape, and stupidly that is where the house is sitting. This is a high rainfall area prone to floods. The house sits approximately dead centre of this flat water catchment area. So of course everytime the area gets moderate rain (often) sheets of water runs down the slope into the house yard. I would like idea's on channeling this water and then using it, although the property doesn't really need the extra water since it has a spring also. I thought of placing a pond in the front yard (approx 3/4 acre out the front of the house) to allow the water running off the hill to create a landscape feature and reservoir, with a spillway that runs into the dry creek bed on the other side of the property. But I'd also like to retain as much water as possible on the actual slope, to make that paddock more arable. Any thoughts? I can't measure the slope but my guess is that it's about 30 degrees in the steepest parts with a basin in the middle that currently has two large pine trees in it.

A pond is an excellent buffer for rainwater, and it can deliver so much more! If you want to control the water flooding down you could take a look at swales.

Yes. Swales on contour, accompanied with (also on contour) subsoil ripping between the swales would capture probably all of that water, except during the heaviest rainfall events. The swales should have spillways at the ends, and the lowest one should have its spillway feeding the pond.

That way, the water that the land cannot hold would be going into your pond. Keep the pond far enough from the house that any seepage will not undermine the foundation.

For a good read on the 3 basic types of swales, check this out: Understanding swales
That page should help point out which of the 3 methods would be right for your particular situation.