You probably want to install a current Java Development Kit from Sun/Oracle.Go to http://java.sun.com/javase/downloads/index.jsp.
If you install the 64 bit version of Java, install the 64 bit version of Eclipse. Otherwise, install the 32 bit version of both. While 32 bit Java is perfectly adequate for most applications and it runs on a 64 bit operating system, pretty much everything is transitioning to 64 bit today just because of the memory size of new machines.
When you add the M2E plugin for Maven support in Eclipse, it will install a built in version of Maven. Eclipse allows you to select for each individual Maven build an external install of Maven. You may want to download onto your machine specific versions of Maven required for certain old and new Maven projects. Some projects will only run on Maven 2 (at least without being converted) while others may only run on Maven 3.
Download and install the latest version of Eclipse. Go to http://www.eclipse.org/downloads/ and choose the Eclipse IDE for Java EE Developers. Again, even if you have a Windows 64 bit desktop you probably want to choose the 32 bit application installation.
You need to add the Maven Eclipse plugin and probably Eclipse support for the Subversion and Git source control systems. If you work with projects that use AspectJ, you should add the AJDT plugin. Go to Help - Eclipse Marketplace. Type a search term like "maven", "subversion", "git", or "aspectj".
There are two versions of Subversion support, Subversive and Subclipse. The Subversive plugin has become the standard choice. The first time you use SVN you will be prompted to install a system specific connector. The SVN Kit connector is 100% pure Java and available on all systems.
After installing the M2E plugin, you can go to Window - Preferences - Maven - Installations and configure external directories that contain alternate versions of Maven you may want to run in batch mode to build different projects. The interactive and Eclipse integration features of M2E do what they do and are largely version agnostic.