Switch and server connection questions

I have a server with an added in pci labelled as 10G 2-port Ethernet/Copper NIC and the it has a built in 10/25Gb 2-port Fiber Optic NIC.

I have SFP to RJ45 1000Base modules - this means 1Gb instead of 10Gb right.

Also the switch has all fiber 10Gb ports configured.

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My questions are: Can you or can you not mix 1Gb and 10Gb speeds on different ports on the same switch? (Does it depend on the switch or is it bad practice?)

Cat6 cables only support 1Gb right? (Package doesn’t specify details). I think it only supports 1 Gbps because I think cat 6a is 10Gb.

1000Base SFP is 1Gb right?

10GBase SFP is 10G right?

So I would need to buy either PCI Fiber NIC cards probably.

Also all the labels and packaging for these only show “G” and “Gb” so I’m assuming Gigabits… and Gigabits per second.