I can't seem to change folder or application icons anymore with Get Info.

I copy then paste the png/ico/icns to the part where you're supposed and it comes up with this >> http://www.imackid.net/help.png

I've been able to.

Click the folder > Get Info.
In the popup window, click on the icon. It will have a blue "highlighted" tinge around it.
Drag your image to the original icon.