There's a reason they are called queers. If that isn't queer, I don't know what is.
Not a good argument to use. Heterosexual couples engage in oral and anal sex as well. If you get asked about that and say you oppose that as well, then it undermines the argument against same-sex marriage by looking like you have a much broader agenda. Same-sex marriage would be wrong even for a celibate couple because of the example it sets and confusion it causes to children and how it undermines the traditional, biological family structure, which is an absolutely necessary social construction to tame the worst instincts of man and promote public health and economic well-being.
Male penis, male anus is the queer part.