When you are installing an extension and get an error the exact message should help us to determine what type of error is occurring or where to look for the problem. I'm not sure why you would be having problems like this, is there a reason you need to uninstall the extensions after they have been successfully installed? If you are only having problems installing extensions after you have removed them this may be a clue about the problem.
In regards to your issues with CSS Menu Writer wizard when are you getting these types of results with the new levels and css code and js code references? If you only have this problem when editing the menu it may be due to how you are editing it. If you want to make a change to the style of the menu you should use the edit theme option from the property inspector.
For the current option you just need to select the option you would like to have for the current page. I like the 'entire navigation route' option best.