I think that would be more "bir ev nasıl arıyorsun?" Modifiers tend to go right before the things they modify, and at the beginning of the sentence, "nasıl" is more associated with the house than with the looking. (But let's see what the native speakers say about it, because I'm still getting the hang of Turkish word order... =) )
Yes I agree on that. When you put nasıl before the noun it becomes more like an adjective (what kind) and when you put it before the verb it becomes more like an adverb (how). However, in daily speaking it's not that strict and both translations can be understood depending on the context.
By the way the direct object always takes accusative ending if it's not next to the verb even if it is indefinite. So it becomes like (Bir) evi nasıl arıyorsun?
Good job ! :)