Can I create and modify the project Schedule directly from the web portal?

Yes you can. There is a small number of the more powerful Project Professional 2010 features that are not part to the PWA (Project Web App) scheduling engine, but for small project schedule’s PWA is more than adequate.

It should also be pointed out the project schedules that were originally developed in PWA can be opened in Project Professional. This assumes that the user / project manager has access to Project Professional and is a member of the Project Manager’s security group.