How can I add new user to my workspace?

User management and permissions#Inviteusers

What are supported browsers by TDS platform and its applications?

Supported OS and browsers

What client do you recommend for remote desktop access?

To connect to Windows servers please use Microsoft Remote Desktop, Remmina or other RDP capable application.

Linux servers are typically managed remotely via SSH using terminals. However you can also install desktop environment and then deploy and use some of the remote desktop solutions for Linux based servers like Apache Guacamole or X2Go (recommended).