Ignore Rainbow, its a usual spammer pretending to be of some use other than a toilet.
I dunno what viber is but gmail NORMALLY works, sometimes it doesnt though 🙂 Nothing VPN cant fix. Skype never had a problem but if you wanna videochat, pray to the god of internets, speed varies greatly. Linked in works like a charm.
Emei-Chengdu have a shuttle bus going so just learn where it is and you can be in Chengdu quite fast 🙂