Post 1: Which Eclipse version to use?
In my journey from MS to Open Source the first thing to get to know was Eclipse, and IDE that is most used for development of java projects just like Visual Studio is most used when working on MS platform.
Having worked with VS since back in 1995, when the IDE for Visual C++, Visual Basic and Web application development used to be different (MSVC, MSVB and Visual Interdev), to the current times when pretty much everything on MS world can be done using Visual Studio, I know that for the IDEs there are different versions and there different editions. Version is obviously something that comes over time with new features, functionality and bug fixes for earlier version and also possibly performance improvements and editions are more of functionality grouping that helps target a particular kind of development community.
It took me a while to understand that Eclipse had its versions more as names like Kepler, Luna, Mars and these are alphabetically sorted, so Mars is the latest in these. In general it isn't an issue for I have got my alphabets right, but it still took a few seconds to resolve it especially for close versions like Kepler and Luna. As of writing this, Eclipse Mars 4.5 is the latest stable build available for development work.
Visual Studio had a similar concept of having code names like Everett, Whidbey, Orcas etc, but these were used only during the alpha/beta kind of releases. Once the product was ready to ship it would typically be versioned using the year of release, so it was always easy to know which version came after which one, like Visual Studio 2015 being the latest in the series.
Similar to the different editions of Visual Studio, Eclipse also has variants that can be downloaded and installed as per requirements like IDE for Java developers, for Java EE developers, for PHP developers, for C++ developers etc. Recently they have also provided a proper installer that can be used to install the required version and edition.
In case you do not want to download and create your own setup, you could very well use the cloud hosted environment as well called Eclipse Che, similar to VS Team Services.
So much for the right version/edition of Eclipse, I am currently using Mars.1 Release (4.5.1) Eclipse Java EE IDE for Web Developers for my current Java based web application project.