Yes, ADAT, coax SPDIF and AES/EBU may all be used simultaneously and independently - aside from clocking (all digital I/O must use the same clock).

So I can make 2 submixes and send 1 to spdif and 2 to Aes? Great, thanks!

In submix mode you click to any HW output you want
(no matter whether mono or stereo, analog or digital or external device connected through ADAT, AES or MADi ...)
then you turn the fader from
- HW inputs to add audio from devices that are directly connected to rec device (to get audio in near-realtime) and
- SW playbacks to add audio comping from the PC (DAW, any other application)
to create the submix for this particular output.
By this you can create wonderful monitor submixes while singing / playing through a backing track from PC which comes from SW playback channels and you can add your connected instrument and/or vocals to the submix for your headphones and you hear vocals as well as instruments without any lag, to put one example.

I see. So instead of UCX where we have only coaxial Spdif/Aes choice+ADAT now in UCX II we have Aes (XLR balanced)+Spdif/Aes unbalanced coaxial+Spdif/Adat optical. And we can send/receive 3 types of digital signals the same time, right?

They will have to share the same clock so that may put some constrain to it. If U recieve 1 signal you can output to all channels absolutely. With more than one digital input active I think you are in wordclock territory which is an option with UCXII. Someone else can give you a better answers to the implementation of that.

Clock sync is paramount with digital input from multiple sources, not just the same frequenzy, but sync. There can be only one master(clock) as RME so eloquently put it in the manual.