That view would mirror the rest of society. There are monogamous atheists. There are celibate atheists. There are promiscuous atheists. There are homosexual and heterosexual atheists. The same applies to any other grouping of humanity.
Atheists and many other people view sexuality as a part of human life, not subject to the arbitrary demands of any deity or the control of government.
This does not mean that secular humanists are necessarily promiscuous. There are practical reasons to exercise caution about sex:
Like most secular activities altruism and reason, not morality , is the guiding principle in play. Self determined control is the important issue. This precludes the control of sexuality among consenting responsible adults based on "standards of morality" or government regulation.
Atheists do not care if someone is gay or a lesbian or anything that may make you different. You are who you are because that's how you turned out. Many have become Atheist due to religious hate against sexuality.
Atheism is NOT A RELIGION. It has no rules. Those are given by morality. Every atheist has different opinions.
There are no categorically atheistic views on any topic except a general lack of belief in gods. Apart from that atheists are simply people. They do not all think alike and with one mind such as theists. You have confused atheists with theists who generally hold religious beliefs as a group.
That is not a question. Atheists view friends as friends.
What you have described is simply a family that does not believe in gods.
Suffering and dying exist. Existentialism has no part in atheism.
Sexuality exists, just like new, fun big words!
This does not really have to do with extentialism, But we atheists view sexuality as a healthy part of an adult's life.
There is no impact. If people don't like people of a different sexuality, it's because that's just how they think, not because they're atheist. There isn't an atheist book about what you should think about heteros/homos/trannys etc.
Being an atheist does not mean that you don't have the same feelings of love, hate or indifference that are experienced by those that are not. these emotions are built into every human being and they are what help the human race survive against even their own evil intentions.
because there is nothing but yourself
There is no atheist position on this and many issues. Atheism only is the position that there is no god or supernatural powers. As far as sexuality, atheists may be celibate, promiscuous, monogamous, polygamous, professional or any other sexually related position. Atheism has no comment or control on a person's private life.
Money and career are different among demographics, so the opinion of such also differs. Secular humanism, as a philosophy, really has no bearing on either; money and your job are objectively measurable and assessed.They are necessary to thrive.