Can my Roon Nucleus be used with a non-Roon-ready DAC?

I have questions that are due to my limited knowledge, so I am turning to this wise crowd for the answers.

I own a Roon Nucleus that lives in a closet with my cable/modem and is attached directly to the Nucleus via an ethernet cable.

My audio system is about 35 feet away. It consists of an integrated tube amp, DAC/Streamer and a power conditioner (and speakers, of course). The DAC/Streamer is connected via an ethernet cable to a wi-fi extender (so that I don’t have to run 35 feet of cable from the modem to the DAC; not to mention, the WAF would be zero for that solution).

A friend recently brought over his DAC with an Innuous server. I LOVED his DAC!! It brought just the qualities to my system that I was looking for. But, his DAC is not Roon ready. This led me to several questions which I’m hoping you can answer:

1)    Is it possible to make a non-Roon-ready DAC work with Roon?
2)    If I were to get an ethernet switch, could I connect the switch to the wi-fi extender, and then to my Roon Nucleus? If so, would the Nucleus be able to act as a server for the DAC? 
3)    Assuming that the (nameless) DAC is at or above the quality level of the Innuous server, to what degree might the Innuous be contributing to the quality sound I was hearing?

I am purposely being vague about both my specific equipment and my friend’s DAC as I am asking these questions for general purposes, not to get feedback on my equipment vs my friend’s.

Any help you can offer will be appreciated.