Yes it goes on your arm although some have had success with alternate sites I don’t use them because if I get a faulty sensor I want to be able to get a replacement from Abbott. Skintac will make sure the sensor doesn’t come off (I had a some that popped off after a few days before I started using Skintac).
I had a Blucon Nightrider Transmitter but it broke last month after less than six months of use. I just got the MiaoMiao in the mail today and it was very easy to setup and it’s waterproof unlike the Nightrider. Much better customer support as well with a 1 year warranty.
The Libre sensors themselves are pretty accurate (usually within 10mg/dl of finger stick) but it varies from person to person. It does show trends but currently without a third party transmitter no alarms. The second generation with alarms just debuted in parts of Europe though. I’m overall pretty happy with it and it is more affordable than Dexcom unless you can extend your Dexcom sensors. Btw, I love the Spike app that you can use with the third party Transmitters. It’s absolutely awesome, easy to use and frequently updated with new features.