I currently have two different TestSuites (SUITE1.XML and SUITE2.xml) with different configurations (e.g browsers, Os)...
I call both SUITES inside testng.xml to run
Yes, you can do this by using "suitethreadpoolsize" attribute of testng
Refer the testng's official website for more details http://testng.org/doc/documentation-main.html#parallel-running
Thanks!