Yeah if you don't have any experience with heads i would have a mech look at it after it is removed. There are a couple of possibilities.
One is that a crack has developed allowing water to seep into the combustions chambers. It can be a very small hairline crack and hard to see. The second is that thread itself has slightly warped or twisted due to the excessive heat. If it is warped, then a new head gasket will not be enough to seal the gap when it is torqued down.
What they do with a warped head is take the flat surface and have it milled down enough to make it come flat again.
If you pull the head yourself be careful and try not to disturb the gasket when you pull it off. That way you can look at the gasket and see where it has blown out, look in the cylinders and see which ones look like they have been steam cleaned, that will tell you where the water is ending up too.
Head removal and install is a cake walk on the 1.3/1.6 engines. You don't even have to remove the intake and exhaust manifolds to get it out of the engine bay.
If you download the FSM(Field Service Manual I think it stands for)? for your engine it will have a step by step that shows you how to install and remove the head. Here's a link, download the one that fits for your rig.
http://www.suzukiinfo.com/sierra/