You could write it that way but in the past I have read that saying 'casa tua' is a way of placing more emphasis on 'tua'.
Yeah I guess it's more to do with emphasis if the noun (casa) is before the pronoun (tua)
I read somewhere (maybe it was the "Possessives" lesson?) that some key phrases don't follow the normal form for possessives, and "casa mia" was the example. So instead of saying "la tua casa" you would say "casa tua"...I guess. :)
'La tua casa' means your house, but 'casa tua' puts more emphasis on the 'tua' and it translates to your home instead of house. Its the same with mia, it would turn into 'my home.
I think I understand your logic, trying to avoid double negation but the correct phrase would be "I have never seen your house". The double negation is still avoided. However, the correct positive sentence would be "I have seen your house." Hope this helps.
Why is it not " non ho mai veduto"? Why for certain conjugations do you add the "sto" rather than "uto"?
vedere (to see) is one of the irregular verbs, conjugated like this in passato prossimo:
ho visto ( I saw)
hai visto (you saw)
ha visto (he/she saw)
abbiamo visto (we saw)
avete visto (you saw)
hanno visto (they saw)
Maybe to emphasize the possessive 'tua', because the order doesn't affect the meaning.