The full suite should be available in HTML5 by the end of 2017
The current version of ENGAGE™ suite depends on Microsoft Silverlight so the browsers currently supported are Internet Explorer, Firefox and Safari. The new HTML5 modeler which is currently available will work on any browser.
No, ENGAGE™ is "browser based" therefore no client instal is required.
ENGAGE™ is a cloud hosted SAAS product which means there is no installation required of any software your network.