Reply To: questions about davening and answering "amen"

thanks, WIY and sam2.

Since I’m in the shul anyway, would it be OK if I said the silent Amidah along with everywhere else even though I was already yotzei, keeping in mind that this should be a voluntary prayer? Would it make a difference here whether I davened alone or with a minyan, since davening with a minyan is preferable? Would it make a difference whether I davened mincha gedola or during the zman of mincha ketana, which is the same zman as I would be davening the second time?

I just don’t feel comfortable standing and pretending that I’m davening when I’m not. Can I answer half-kaddish even if I didn’t say ashrei? How can I answer kaddish if I didn’t say tachanun? And why am I required to say aleinu?