Java Runtime Environment and two updates are installed on my (C:) drive which has very limited space. Can I move them to (D:) or uninstall from (C:) and download and install to (D:)?
Yes, you can safely uninstall them from (C:) and move the software to (D:) drive. First, download and run the Java Uninstall Tool to remove the utility from the first drive and after that, download and install the latest version of the software from the official web page. You will not need any other previous updates because this version replaced them.