"The list is long..." There are a lot of places on the web to educate yourself on the how to's. The journey is more important than the goal. Perhaps. Perhaps not. The worth and cost of acquiring experience and knowledge. Good luck on your journey. Have fun doing it always should be number one, in my book.
1. As artur9 said, there are many different software, music playing programs out there. Your own financial situation will dictate your path. What is good enough for one... Roon is certainly popular with those who stream Tidal and other services. JRiver seems to work for those who archive their own music as you seem to have started out doing years ago. Streaming versus archiving may be a question that you want to answer first before moving forward. Do you want this software to help you find new music or do you have ways to stumble onto new music on your own already?
How do you like to listen to music?(In the background while doing something else, as your sole focus of attention, while traveling only, on a phone, in a car, train, airplane, via headphones, via speakers, are others involved where and while you listen, etc.)
2. Do I need a micro(ultra) rendu (versus another means of streaming from one location to another)? You indicate that you only listen from one spot at this point. So are you trying to get up and running so that you can hear music where you live? Or are you looking to build a system that covers several rooms? The big question...budget? Do you have a turntable? My understanding of the sonictransporter is that it's a cd ripper/storage/player device. It should be able to output a signal to a dac which could feed a preamp or an amplifier. You would not need to tether it to a router to listen in one spot, only if you are looking to share files with other locations.
4. A microrendu is a computer. But a very specialized one. Yes one can use a laptop, or desktop computer for that matter, with the correct software, like JRiver, to replace a microrendu(We are in danger of making a "microrendu" an "aspirin" if we are not careful here. Both were/are proprietary names at first.) Does one want to use a specialized streamer versus a laptop/desktop? You may find enough of a difference in the resulting sound if you compare/use a microrendu versus another streaming device. The associated equipment in your system will have an effect. How the equipment plays together will determine your satisfaction with the resulting sound. What is your budget? How much time do you want to invest in the set up of your music playing system?
So you have a Devialet amplifier. What is the model number? I ask because the more information about the equipment you presently have that you give us, the better we can understand your specific situation and thus give you hopefully better help.