Poweredge T320 RAM mixing questions

I have a T320 and some spare memory modules.

The T320 currently has 2 x 8GB (Samsung part no M393B1G70BH0-YK0)

This is actually confusing already since that RAM module has speed of 1600 MHz, but the idrac sais 1333 MHz, (***?) maybe anyone can clarify this? Is the idrac output wrong?

Can I, and if yes how, mix those two existing modules with:

- another 2 x 8GB (Samsung part no M393B1G70BH0-YK0)

- 2 x 4GB (Samsung part no M378B5273DH0-CH9)

- 2 x 32GB (DELL part no SNPM9FKFC/32G)

How is mixing memory in the poweredges in general?

Thanks for any help!