From my experience changing the installation path of Visual Studio is possible but may cause a lot of problems later. I would not try to change the location Microsoft where thinks an installation have to be. Instead I would use the NTFS soft link feature and pretend that Visual Studio and some of the other components are installed on C:\Program Files\... where as in reality they are located on the RAM drive:
Format your RAM disk with NTFS (if it is not already in this format)
Copy the directories you would like to mirror to RAM onto the RAM drive (better use command line, not Explorer) - the exact target path on the RAM drive does not matter
rename the original directory in your Program Files directory (e.g. "Visual Studio" to "Visual Studio_".
Create a symbolic link from C:\Program Files\Visual Studio to your ram drive (R: in this example):
VSIX is a Visual Studio extension installer. You must have Visual Studio 2010 or newer in order to install them, but you should be able to install it by double-clicking the .vsix file. Alternatively you should be able to install it from within the VS Extension Manager (Tools->Extension Manger)
See more about VSIX files at Quan To's Visual Studio Extensibility blog