Yes to the first question and most likely yes to the second question, but I haven't tried that yet. But it is an uncomplicated adapter. I use it to connect the LG Ultrafine 5K monitor to the network, which in turn shares the connection via Thunderbolt 3 with the MacBook Pro 15". Even this "trouser slip" works flawlessly. I can only recommend it (it's also nice and black).

We have noticed with our MacBooks that the adapter reproducibly downloads at almost 1 gigabit/s in the first few seconds of the cnlab speed test (the app, not in the browser), but then drops down to 300 to 500 Mbit/s. Uploads, on the other hand, always go through the line at just under 1 Gbit. We have observed this with at least two adapters and can actually rule out other factors: iMacs do not have the problem (connected to the same switch), nor does an older MacBook with a TB-2 LAN adapter.