8. Can I update orders using Mobile Assistant?

Using Mobile Assistant you can't update your store orders, you can only check them.

In case you need some solution to update your orders, statuses, e-mail customers, and more you're welcome to check Store Manager solution that is a windows application and offers more extended functionality:

http://emagicone.com/products/

There's free trial available, so you're welcome to check it free of charge!