When using EC2, you usually don't have to worry about bandwidth. Just select the best region for your users.
In terms of tweaking, when creating the EC2 instance, you will have to select an image for it, perhaps you want a Windows server if you use a non- dotnet core version of server files. Be very careful about your credentials and firewall rules, if you don't want unexpected login.
Audio driver? Not sure why you need it, but when using Microsoft RDP, the sound just works, no tweaking is required.
And you definitely don't need a GPU, which is usually used for AI-related work.
Take advantage of your free tier quota before actually paying anything.