All of these issues seem like they may be dust and dirt related, so cleaning the machine may help. Dust gets stuck to the print heads and causes ink to drop onto the prints.
Except the horizontal lines, that sounds like banding and is often a feed-rate issue. You can fix that by making sure the paper is set in the computer to match what the paper really is. If it's already set to the right type the manual may include a section on troubleshooting banding/print quality issues.