Wasn't their a conversation about this in one episode where they were asking something like if one parent was human and the other Wesen which would the child be? I do remember Hank asking what would happen if the parents were different kinds of Wesen.
It's new territory (much like Kelly could be, given he is a child of Wesen and Grimm); I guess it will all come down to the child's genes. One side may be more dominant than the other. Some have expressed a wish in other forums for Monroe and Rosalee to have twins. Perhaps one could be dominantly Fuchsbau with hints of Blutbad, and the other could be the opposite.
It depends. I think if they're bothering with it, it will be different and able to woge into both, which would be rare. That usually would only happen will genetic engineering. Otherwise, the child would just be one or the other.
In "Stories We Tell Our Young" Monroe & Rosalee give Nick & Hank the "Wesen birds & bees" talk, including that with mixed-species Wesen couples such as themselves, their child would be a "Vorherrscher" (German "prevalence" as defined in this Wiki) meaning that one Wesen type will dominate - though apparently there can be health risks for the developing child. ("But we don't care...as long as it's healthy!)" When asked repeatedly at conventions and in interviews, Silas kept repeating that Monrosalee's child/children would be "Vorherrscher". So if the Grimm writers stick with this, Monrosalee's children could be Blutbad or Fuchsbau -- not hybrids. [Imagine the sibling rivalry among the triplets, especially if one is Fuchsbau and the other two Blutbad, or vice versa! Not to mention their Blutbaden and Fuchsbau grandparents' reactions...] Given how severely the Wesen Council reacted to even a possible Wesen mutation (Grausen), we can only imagine the drastic steps they'd take to prevent hybridizing between Wesen species!
It was explained in the show. Human/wesen end up half powered and partial woge of the wesen parent. Mixed wesen couples the dominate gene is what you usually get.
It's sounds like what happens with human genes for hair, eye, height, nose, etc. So you wouldn't end up with the fuchsbau fur, blutbad nose, fuchsbau eyes, and blutbad teeth. The human form would be something like Monroe's hair, Rosalie's nose, etc. But woged would be one of three things. Blutbad, fuchsbau, or human (assuming the wesen genes were able to cancel each other out.