This is certainly am late getting to this but I thought if anyone else wanting an answer to the same question came along I could say that I bought mine here just for making baby food... and I love it. In fact, I'm here to look at buying a second one because I accidentally melted the top on mine. :( Whoops!
For small batches of baby food I love this... but I've used it for other things like homemade salsa and to chop garlic and thought it was only okay at those.
Yes, add water to puree baby food. Only add formula or breastmilk if you are going to immediately serve it (do not freeze or refrigerate food with formula or breastmilk added).
When we add water, we add about a tablespoon at a time. Green beans need less water added than, say, squash or sweet potato. You don't need to add hardly any water to pears and other fruits, so go easy. You can't really get the water back out once you add it, ha ha ha. Look at wholesomebabyfood.com for recipes and instructions on how to add water or process each fruit/vegetable.
We have been using this since we got it in 2010. We started using it for baby food in 2012, and are now ordering our third blade for it (when you consistently puree hot food, the plastic cracks on the chopping blade and renders it unsanitary). It is really a great appliance.