Welcome to the Cocoontech forum Marc.
Is there a way to wireless control the Sonos unit from another room with a Echo from Amazon?
From the following article on Wired Magazine posted on 08.30.16
it appears that there is:
Amazon Echo Now Lets You Control Your Sonos Speakers
Does the echo need to plugged into the Sonos unit or can it control the Sonos system wireless through the wifi?
Also. can an Echo give commands to the HAI omnipro system?
You can today do this with software integration.
Read right here on Cocoontech relating to CQC and Homeseer and just recently
Amazon Alexa adds new "Smart Home Skill API"
Today utilize Homeseer 3. Many years ago put a mini serial server on my Russound set up such that I could control it via Homeseer Touch and Omnitouch Touch screens and Russound Keypads.
Integration between Homeseer, Omni Pro 2, Amazon Echo, Russound and Sonos works today just fine.
I do not utilize Sonos today. There are many Russound users that do utilize Sonos today.
I am still tinkering here with the Amazon Echo and have one Homeseer touch client running Windows 10 which integrates the Amazon Alexa Homeseer Application / Homeseer Microsoft Kinect application (they talk to each other) with a 15" multi touch monitor. This configuration talks to the Homeseer mothership running on Ubuntu 16.04 64 bit today. Here have integrated Homeseer Microsoft and Ubuntu for my automation stuff.