You are asking in the wrong forum, there is one dedicated to Solaris questions.
About 1), that depends on your definition of free. The kernel and many parts of Oracle Solaris are proprietary,
other are open source. You can download, install and use Oracle Solaris for free (but without support and upgrade) if you comply with the
OTN license requirements.
There are also
OSes based on Illumos (OpenSolaris fork).