It took it 48h roughly to sync, which is pretty good. CPU temp was in the 70s / 80s, but that should be no problem for modern chips. In fact, high end desktop CPUs can operate even close to 100C before throttling.
I would just position the thing on top of something else so it can more easily suck in air from the bottom for the little Orange Pi fan.
Good to finally know what caused these guys issues...
Personal opinion: it's easily good enough to check the pool's dashboard when on the go; if you really need to see the dashboard, you could create an SSH tunnel, VPN into your network, or potentially setup a Tor v3 hidden service with authentication. The latter might be the safest solution honestly.
Especially in current international state of affairs, there's lots of viruses, hacks and malware going on as well guys, so beware, update your stuff and stay safe. Don't decrease your security in any way if avoidable..