1) Your first choice is much better (although it slightly sounds like 'which' refers to 'street', not 'house'). The second isn't correct. The most typical way to say it, though, would be... "I was on the street where he lives, but I didn't know which house was his." 2) Your first choice is correct, but, more typically, it would just be... "I don't know the way to the church." If it's your church, then you might say... "I don't know the way to church."

Hello! I can't give you the "correct" answers but I can give you some insight: a natural English speaker probably would not say any of these four sentences. I agree with DanN completely. For #1, I would say "I was on the street where he lives, but I didn't know which house was his." For #2, I would say "I don't know the way to church."