You shouldn't have any rendering issues with WP using your card. I'm on the 290X and I can render 10K worlds and process them without much issue aside from the time it takes.The most likely scenario is that the install is somehow faulty. Uninstall, reboot and reinstall. Use a side app like CCleaner or RevoUninstaller to clear your system of the last install completely if it doesn't work the first time at reinstall.
As for the issues with the brushes and tool sets, WP can be a bit finicky sometimes with snapping and takes some trial and error to understand it. All the tool bars can be re-enabled if you loose them by resetting to the default work space. Once you do get everything how you like it, be sure to save your work space for fast loading in the future.
If for some reason the display issues continue and only persist while using WP then something else has occurred beyond simple measures. If glitches are occurring in other apps and games chances are the GFX card is damaged, which should be fine since XFX does lifetime warranties.