Basic Digital questions

For a short time I had a computer running JRiver through a little iFi DAC and accumulated digital files of various types. Not long after I got everything working the computer crashed and I have not replaced it. I now want to start again and get another computer, mainly dedicated to my audio system, but used for work when I need it. I also want to stream, as it could possibly be the only way to hear some music in the future. Furthermore, want to be "done" as soon as I can in this process, or at least as "done" as one can with digital audio. I thought I would ask a few questions before I start spending money and would appreciate suggestions any of you might have.  

If I have a laptop (PC, fanless) that has Wifi, Bluetooth, etc., would there be any point in having a DAC with those features? I imagine that if I want to use my phone I might need a DAC with Wifi. I don't need a DAC with a line-level or phono preamp.

I have been told that signals are best through Ethernet, not Wi-Fi. Have people found this to be true?

If I watch a movie through Netflix or Amazon (or, ahem, a disc) will I be able to run the digital information from the device to the DAC? I do not have an actual TV and do not use cable.