1. The USB 3.1 ports come in different colours because it indicates the difference in the types of those USB ports. The USB 3.1 has two types of ports viz. Gen 1 and Gen 2. The Gen 1 port comes with a transfer speed of up to 5GBps and it is a less brighter shade of blue with SS symbol next to the port whereas the Gen 2 port has a transfer speed of up to 10 GBps and is a brighter shade of blue which is marked with SS10 next to the port.
2. The best and fastest supported SSD for storage would be Samsung 980 PRO PCIe 4.0 because it is not only the flagship SSD but it also supports the PCIe 4.0 slot. This will provide high read and write speeds.
3. The TUF Gaming is basically a product series from ASUS which focuses in making durable and reliable gaming products. It is a joint effort taken by Cooler Master, ASUS, and others to create products for a great gaming PC.
4. Yes, it is possible to use a TOSLINK cable to connect his speaker system as this motherboard has a optical S/PDIF out slot which will support the TOSLINK cable.
5. The ASUS X570 PLUS motherboard comes with an AMD AM4 socket. So considering the requirement of Christian, I would recommend him to use the Intel Core i5-9600K Coffee Lake 6-Core 3.7 GHz Processor because it is a best for its price and specs too.
While checking the galley of pictures, Christian got scared... Why the USB 3.1 ports come in...