Your apache error log looks normal.
This link explains the correct uninstallation proceedure better:
http://www.apachefriends.org/en/xampp-windows.html#524
You have a system issue if you can't read the event viewer. Not sure what that could be as it might perform differently in Home compared to Pro. You may need to research that fault and error message as it is a system problem.
WAMP could still be an issue if the paths to any of the WAMP components are still being accessed via the registry. Particularly PHP as this error you get seems to be a conflict issue.
I would still uninstall WAMP as you don't need it with XAMPP and make sure the paths don't include a path reference to the WAMP's php component.
Reboot after doing an uninstall of WAMP so any changes made in the registry can be recognised.
In the XAMPP welcome page there is a menu item phpinfo(),
Click on it and you should see your PHP information.
Look for the path to php and any abnormalities that don't point to any of the XAMPP paths. This might expose any issues with WAMP and XAMPP.
Control Panel>System>Advanced>System Variables>User variables and System variables will give you path information you might want to check. I found that copy and paste into a text editor made it easier to read the long paths. This also enabled me to edit them if required.