When you are receiving it in Missionary do you ever put a pillow under your ass?

If we're doing normal missionary, yes, a pillow helps get the angle right, but most of the time we just do it with my butt at the edge of the bed.

Yes

I put my hands under to change the angle but only with my legs up.

We used to use pillows. Now we use a Liberator Wedge pillow and it works much better. It's especially useful for anal.

If I'm on my back I am usually on the edge of the bed with my knees up and he's standing, we don't really do it standard missionary.

As a dude I sometimes suggest it. Depending on how our bodies line up it can be helpful.

For gay partners it’s something I highly recommend; it makes the angles all line up much better than without