I agree with dave
here. Nothing wrong with being cautious. However, is the OP going a bit to far? While we can discuss that for hours, it really comes down to how the OP feels, and if the OP feels that the actions they are taking are enough to protect them.
Back in the day, I think what the OP is doing would be warranted, as there was ways that "the web could jump out and get you". Nowadays, if you are behind any kind of Firewall (which, as has been pointed out, is on by default) or NAT router, you've got a good layer of security already in place.
To each their own I guess. However, that is part of what I will call the excitement of this field. It is always changing and growing. Each of us should always be open to listen to others suggestions and ideas, so that you yourself can remain current as much as you can.
I'll still do my best to try to help test this out this weekend, so that I can help answer the root question.
--Brian