Since you need 7 finished projects and don't have a lot to work with, have you considered pillows? That would eliminate the need to use such widely varied fabrics in one project.
In answer to your other questions. Denim generally sews better with a denim needle. The "holes" in the T shirts will close up after washing. T shirts usually work better in all projects when backed with some type of interfacing to prevent stretching when sewing.