So how comes I am asked the same questions in Japanese, and even by people I have known for some time (who may ask again and again, several kind of strange questions) and who visibly feel comfortable with me ?
There are no doubt some people that may appear visibly comfortable with the foreigner, such as yourself, but are you really sure about that? Have you ever asked the person to consider what they are saying? Well, chances are that you have done so, and if your comments are of any indications, the answers you received weren't satisfactory, yes? Perhaps if you reversed the trend by asking them bizarre questions might job some reactions, but then chances are you'd only get referred to as the weird gaijin, so that may not work either. I suppose it's best to find the nihonjin that are on the same level as you are, conversationally, and ignore the others except for basic salutations....
Chances are good, however, that the persons in question you are referring to have never really considered what their questions indicate, if they are weird, strange, offensive or whatever...it might be good to inform them of this, if you have a mind to do so...but then, depending on the person, it could also be a waste of time.....I've dealt with folks here, in the Great US of A who when dealing with things they are familiar with can talk on an even keel, but try to explain something they are not familiar with, they also begin asking or commenting in a rather naive way...but to each their own....I do get annoyed when I still meet people who think that Japanese people all are geishas and samurais and can't figure out how they make them Toyotas and Nissans....
But then, the reverse is true, when I get asked by the Japanese if folks in the backwater state of Oregon still have cowboy and Indian wars...
otagaisama desu