Where can I see the work load for a team?
From the main menu click to the resourse icon-> “Resource workload”. Filter for your Team or from the Project view of your project click on “balance” icon. From the load page you can eventually add more people to inspect on-the-fly.
https://twproject.com/support/using-twproject/work-planning/work-load/
Can I plan activities day by day?
Yes. For each assignment you can define the working plan. From the “workgroup” box on a project (or on a department) or directly from the assignment click on “see plan”.
https://twproject.com/support/using-twproject/work-planning/resource-work-plan/
How can I set priority on a project?
You can set priority on assignments. https://twproject.com/support/using-twproject/projects-and-tasks/assignments-who-is-working-on-projects/
How can I see assignments for a resource?
From the Project list page select the desired resource in the assignee field.
Does work done, affects work load estimation?
Yes. By default Twproject uses remaining work (work to be done – work done) to compute the load for the future. If you didn’t done you work fro today you will probably need to work a bit more tomorrow 
.
https://twproject.com/support/using-twproject/work-planning/work-load/
Can I plan activities using ToDos?
ToDos can be used for planning users activity. Using the ToDo planner you can set the day you want to close an ToDo; estimated work on the ToDo give you the work load for that day.
https://twproject.com/support/using-twproject/issues/kanban-organize-projects-to-do/